So I decided to take the plunge and drop a small block in my 91 yj but I have no idea what transmission or transfer case to use. I'm pretty new to this and don't know the difference between all the numbers. Anybody have any suggestions on what to go with or maybe a site that breaks down the differences between them all?

A little more info might help.

What small block are you contemplating? Ford, Chevy, Mopar...?

What tranny do you want? A 3-speed or 4-speed automatic, or a 3, 4, or 5-speed manual tranny.

Are you looking for a full-time or a part-time transfer case?

I will most likely be going with a 350 gm small block. I'm leaning towards a 4 speed auto but I wouldn't be opposed to a stick if I could find one. But I think I need a part time transfer case cause it will see a bit of on road use.

If you go manual...

An NV4500 transmission with an NP-231 transfer-case will work; provided you have the correct input shaft.

If you want auto....

I will let someone that knows the specific parts chime in. I want to say it is a TH400 that you need.

There has been a recent thread covering some of the issues and work-arrounds.

Probably easiest to use the Chevy version of the 231 and install the Jeep's short tailshaft (or a slip yoke eliminator) to shorten it for YJ use, no need for adapters, then.

The 700R4 or 4L60E OD automatic to match the year of the engine and electronics you use would be the best automatic trans. No adapter needed to the engine, of course!

Another option on the Manual trans would be the NV3500 5 speed. It's lighter duty compared to the NV4500, but it shifts smoother, weighs less and probably costs less, too. It and the Chevy NV4500 use a hydraulic clutch actuator, like the 5 speed you have now.

EFI, either TBI (Simple) or Tuned Port (more upper RPM power) would be the best induction system. OBD-1 ('95 and older) is the easiest to set up.

It might be best to buy a complete running 4X4 Chevy 1500 truck with all the components in place, maybe a rollover, rust-out or rear end total wreck. That way you would have the engine, wiring, sensors, trans and t-case in one package! You could part out the rest and recoup some of the cost.

One thing to consider is whether or not your states' emissions laws allow a swap and what procedure, if any, you need to do to get it to pass a smog test.

As for the T case, either a full time or part time is suitable for on road use. The full time allows a bit of differential action between front and rear for turning, a part time allows none, which is why it can only be used part of the time - off road.

What about a Dana 300? I found a good price on one but I'm not sure if it will work, I'm using dodge axles if that makes a difference.

Anything can be made to work, the D300 is a good t-case and can be twin-sticked so that you have control of the front wheel and rear wheels independently, and can be flipped to work for both passenger or driver drop front axles. You say you are using "dodge axles" could you be more specific? Are you referring to Dana 60's, Dana 44's or even newer AAM's? Check this site out with regards to most of the questions you will have about this swap www.novak-adapt.com as they have both parts needed and the technical information to help you with this type of swap as an entire drivetrain swap is something that is not to be taken lightly with regards to the fabrication, knowledge needed and difficulty in doing. Hope this helps. <img src="/forums/images/graemlins/cheers.gif" alt="" />

Fred R.

That was actually an extremely helpful site. I picked up a set of axles out of a 70's ramcharger, the front is a dana 44 and the rear is a chrysler 9.25".

SBC 350, NV4500 out of a chevy, Dana 300 from a jeep with twin sticks and your dodge axles with around 37 inch tires.
That would be a good start. Then as soon as you can get ride of the d44/9.25 set up and go with d60s, d60/14bolt, d60/ford9" combo and some bigger tires! Don't use a NV4500 from a dodge. If you want an auto tranny find any turbo 350, th400 or 700r4. They will bolt to your SBC, they are strong but you will need a good tranny cooler system.