68 F-100 4x4 Drivetrain decisions...

[JoshT]

Every other board I'm on to discuss this is either oriented to the truck or the particular engines. They are usually biased and/or at extremes. Hoping to get some feedback here that is a little less biased and might help me get my ideas together. A little background on the truck before I get into the discussion, if I don't have one already I'll start a separate build thread on it at a later time.

Some of you have seen the thread and posts about dad getting sick a few weeks ago and passing last weekend (7/13). Most of you probably wouldn't know that the F-100 4x4 in my signature was originally his. He got the truck in the mid 80s from his (at the time) step-dad. The step dad was a good man, but was gone from the picture when I was young enough that I don't really remember him, so it me it was always my dad's truck. Dad usually had a newer, smaller truck as well, my former '84 Ranger for a time, a '90 BII, a 2wd '94 F-150, then a couple of other Rangers, but the F-100 was always there and was the go-to when there was tough work to be done. Around 2006 he got the F250 (also in my sig) and the F-100 got put to pasture. I think he would have been interested in fixing it up himself, but he had already been in the plane crash by that point which lessened his ability considerably, then the medical retirement and other stuff made the finances too tight for playing with something like that. He also knew that I eventually wanted to get and rebuild it, and wanted me to make my own descisions on it. In hind sight I wish I'd made it a priority and done it back then, but i had other projects and priorities, and no room for it in the stable so it sat. I pulled it out of the pasture in 2018, got it back on the road and use it occasionally, but didn't take long to realize that it's going to take a fair bit more work to make it the truck I want it to be. I'll go into more details in the build thread. Got the F-250 from dad in 2021 and the F-100 has mostly been waiting for me to get facilities to really undertake a rebuild/restomod on it. It's still usable, but it isn't something I would get far from home in, especially now that dad is gone (or this time of year with no A/C). On to the point of this thread...

With dad's passing his shop is no longer in use. I no longer need to wait for a place to work on it and it's got almost every tool that I could possibly need. If I can stand to be in there working without him, that feels like the perfect place to rebuild his truck.

While this will never be a regular road tripping vehicle I would like to be able to hop in and drive a few hundred miles away with no concerns. I'm in Middle GA and when I get done I'd like to feel comfortable hopping in it and going out of the area/state. Definitely to something like the Caffeine and Octane meets that @Rick W goes to in atlanta that is about 2 hours, 120 miles away. Maybe some of the bigger eastern Ford meets like Maggie Valley or Carlisle, about 300 and 800 miles respectively. Even better if I can do it pulling a small camper (really, a small single person unit), or maybe a Ranger on a flatbed, in relative comfort. To even get close to this goal I'm going to want a fresh engine (preferibly one with more power), EFI (already have Sniper on it), an Overdrive transmission, upgrade brakes, and A/C.

Currently the truck has a worn out Ford 360 FE backed by an NP435 and Dana 21 single speed transfer case. Front axle is a Dana 44 and rear is a Ford 9". The Dana 44 is converted to disc brakes using a spindle and caliper from a 70s Blazer, and a rotor and hub from a 90s F-150. Would like to swap to Willwood multi piston kit if I can ever souce some good drum brake spindles, mine were lost in the shuffle, but that is discussion for another time and place. Rear 9" will eventually be swapped for the wider 31 spline 9" from later model F-100/F-150, again discussion for another time and place. Truck has 32" tires w/body lift at current, it's either getting 33s/35s and a proper lift, or 31s and no lift during the rebuild, haven't settled on that yet. I'm mostly interested in the engine and transmission for this discussion, just wanted to state what I'm working with now.

I'm considering two routes for the engine, either stroking the FE or swapping a 7.3L Godzilla. Seriously, I know that there are other options, but I will be using one of those two. No LS flipoff, no coyote/mod motor, no windsor. I'm torn on which of the two to go with though. The FE has the originality and period correctness, but definitely has drawbacks for a truck I want to use. It'll be expensive to build, harder and more expensive to maintain, more expensive to feed, and a stroker never has the reliability of a stock engine. The 7.3L Godzilla will be expensive to swap, but you get as much power in a stock package with lots of room to grow. It's also more efficient, parts are available everywhere, actually smaller and lighter weight from what I understand. It does loose the originality, and more difficult to install since noone makes swap kits, but there is a welder, engine hoist and lots of metal around dad's shop.

Rebuilding the FE like I'd want is going to run 2-3k for the stroker kit. Probably 2-3k for a set of aftermarket heads, camshaft, and valvetrain upgrades to support the stroker. Based on the 5.0L I did last year, probably around 1k for machine work on the block, more if I have them assemble it (probably wise considering the investment). I'd probably be looking for a better EFI system to install too, with that much invested in the longblock, I'm not sure I'd want to trust it to a Sniper. All in I'm probably looking at 10K plus for the engine rebuild. When you get into stroker kits on an FE all displacements cost about the same. With a 445, about the biggest I could go on my block, and a good set of heads I'm looking at about 500 hp @ 5k RPM, 450+ lb-ft from 2.5-5k RPM. Of course that is built and cammed as a performance street motor, not a truck engine.

I know that "The Infamous Project" sells complete (all accessorys and controlls) low miles 7.3L takeouts from E-series EV conversions for <$9k, or ~$10 with an automatic transmission. I really don't want an auto in this. I'm guessing that I can probably find even better prices for a low miles engine, though maybe not as low. I think I saw where Ford sells 7.3L crate engines for 5-6k, but no acessories there. Even if I bought the complete takeout I'd probably want to get the accessory relocation kit that is sold for F-100 swaps (wish they did mounts too) and need to buy a control pack to work with the manual transmission. I figure looking at about the same 10k (maybe another 1-2k for everything) to get a running engine swap. Those are around 430 HP and 475 lb-ft stock, Probably better with tuning, and allegedly a lot more available from a simple camshaft swap. Plus you get the advantages of a modern engine. Lighter weight, better metalurgy (aka better wear), more effeciency, and parts available at pretty much any local parts store.

With either engine option, truck will definitely be getting a 5 or 6 speed overdrive transmission and a 2 speed transfer case. The NP435 was a very tough transmission and great option 60 years ago when the truck was built. Unfortunately on these F-100s ford used a Dana 21 single speed transfer case married to a 2wd version of the NP435. I definitely want to swap to a two speed case, but to do so I'd have to replace the entire transmission. They are out there, but in my area a 4x4 NP435s aren't just lying around in every salvage yard. It would cost dang near as much to get one of those in good condition as it would to get something modern with an overdrive. Leaning towards a ZF6 w/ manual transfer case from a V10 Super Duty. Those are rated for something around 700 lb-ft, which is plenty for either engine choice and build I'm likely to do. The shift pattern is backwards from what the truck currently has, but the F-250 has the same transmission (and transfer case) so I'm good there. The V10 used the modular bellhousing pattern, so does the 7.3L and adapters are available to put mod motor transmissions behind the FE, so that is covered. The hardest part of that swap aside from having driveshafts and a crossmember made is that the ZF uses a hydraulic clutch, while the F-100 is mechanical linkages. Some of the transmission swap companies do make a hydraulic clutch master kit for the F-100s. They're more for use in building performance 2wd street trucks, but the body and clutch pedals are the same.

I'm not worried about numbers matching or all original. That went out the window 30+ years ago, and I care more about it fitting me than being original. Dad was the same way. I have no doubt that dad would have gone either of these routes if he were building the truck and able to afford it. Back in the 90s there wasn't as much aftermarket available for the FE as there is now and what was was even more expensive, so that was off the table. Of course the 7.3L gas wasn't around then, but a lot could be done with a Ford small block. I seem to recall that at one point he was considering swapping in a 351w and C6. I know that the 351 was in a retired CVPI that my mom used to drive and he had the auto and divorced transfer case in the back corner of the shop at one time, both are long gone now.

Please discuss these engine and transmission options. I've got a lot to do to the truck before I need to nail down what I'm going to do, but very torn on which way to go. Hoping that discussing it will help me come to a decision. Engine does run, so cleanning up the frame and fixing the bad spots on the body will be the first major components in the rebuild, but I feel like I need to have an idea of what I'm going to be doing on the drivetrain before I have to make any major decisions on those. I might not even do the engine swap/rebuild as an initial part of the restomod (that would be a lot of money at once) and make it a "phase 2" deal, but I have an idea of what I'm using I can pre-plan to make things easier when it does happen. Maybe something like mockup block to build mounts and cross members select headers, etc. while the body is blown apart and before the frame gets cleaned up and painted.