I tried 10w-30 in my 93 4.0 and it was ok when warm, but the first below freezing day the pump just wouldn't. Zero oil pressure. Had to get another ride to work and change it the next day. (Still below freezing. Took an hour to drain.)
Depends on what clutch/flywheel you used. If it's from a 2.9 the starters are the same. If you "upgraded" to the 4.0 clutch/flywheel you'll need a manual starter from a 4.0.
BTW, later models (Not sure how much. Any 4.0 maybe?) auto starter fits the 2.9 clutch/flywheel and is of more compact...
Ranger 4wd rear driveshaft doesn't have the slip yoke up front. It's in the middle of the shaft. So that's a no go.
I'd be surprised if any A4LD slip yoke was different. Probably 4R44E and 5R44E too.
Bed/Cab length does matter. It changes wheelbase. But I don't think a long bed was offered...
Considering how much steel has gone up lately, those bumpers may not be as expensive as you think. At least not when compared to buying the materials to make your own.
I'm a cheapskate so would be more likely to find something close to the right size and local to make work. Like my bar. Was...
In an 88, 4.0 swap is a fair bit of custom wiring if you wanna keep your dash. Almost all the mechanical bits swap though.
4.0 can be bolted to 2.9 flywheel, clutch and transmission. The 2.9 clutch will slip before you do too much damage to the transmission.