4x4 issues\questions 2000 Ranger

[omnisicentfly]

I have a 2000 Ford Ranger 4X4, 3.0 V6. I recently replaced the engine with a Jasper rebuilt and now when engaging the 4X4 with the switch on the dash only my 4X4 high light will light up, no 4X4 low. The switch on the dash is working as tested by a mechanic. Vacuum lines were replaced as well. It is equipped with the vacuum pulse 4X4 system; however, I would like to bypass the vacuum system with manual locking hubs I found for sale here, http://store.4wheelingplus.com/proddetail.asp?prod=15001.70 My question is that even with the manual locking hubs, I do need to engage the transfer case with the switch on the dash, if I am only getting 4X4 high to light up, will the manual locking hubs function properly in 4-wheel? Or will I need to have both 4-high and 4-low available to have full 4X4 functionality? The mechanic that did my engine also mentioned that the problem could be with the JEM module. Just looking for suggestions on possible fixes so I can buy and use the manual locking hubs and avoid using the problematic vacuum system on this model. Thanks for any and all help. If I left any important details out please let me know, the 4X4 is important to me and my only concern with vehicle presently.

 

[adsm08]

The hubs and your lack of low range are in no way related, and yes, you will still have to engage the transfer case to have 4x4. If you lock the hubs and leave the case in 2-hi you will not be in 4x4, the front drive train will just be spinning.

The GEM may be to blame for the lack of 4-low. There may also be other things that could cause it like the motor or wiring.

 

[omnisicentfly]

Okay, so even if I have the locking hubs, because my Ranger will not switch to 4-low, I will not have this functionality. I am more and more starting to suspect the GEM myself as I can hear a noise from the motor on the transfer case. I am going to try and find a GEM and a transfer case motor from a junkyard to test this theory. Where is the GEM located for the 4x4, I have heard behind the glove box or behind the radio and to the left. Does anyone know which is the right location?