Stuka wrote:Some may require adapters. The best chain drive for swapping these days is a NV241 from a JK Wrangler. As I recall they are a 23 spline input, which matches some FSJ transmission options. There is also the 241OR which has a 4:1 low range. Both are mechanically shifted.
Note: I do recall one guy swapping one, but cannot recall what he had to do, if anything.
The JK Wrangler eliminated the speedometer output in the t-case. Instead, the computer uses the ABS sensors to figure on-road speed. So if you use a JK (2007-present) transfer case you need to figure out how to get your speedometer to work. I don't know if anyone makes a bolt on solution for that or not.
For the OP:
A YJ (87-96?) or TJ (97?-06), XJ Cherokee (84-01), ZJ Grand Cherokee (93-98), and WJ Grand Cherokee (99-04) will come with either a 207 or 231 (the 231 replaced the 207 in the late 80's), which is weaker than what came on the full size Jeeps, but it has a speedo output. The TJ Rubicon will have the 241OR that is beefier and has the 4:1 low range but it will have the speedometer output. (However, Rubicon cases tend to sell faster than pizza at a weight watchers convention so finding one is not easy.) You can also find an NP242 (217 in early model XJs) in the XJ, ZJ, and WJ. That gives you an extra option of full time 4HI on top of part time 4HI. All of these cases will bolt up in place of a D300 with no adapters, assuming you find one that is 23 spline and not 21 spline. You'll have to rig up a shifter for the case. Any flag shifter from a full size Jeep should work but you may need to tweak the connections.
In full size trucks, the 241 replaced the 208 in the late 80's.. They're both in the same ballpark for strength but the 241 has some improvements that make it worth pursuing.
If you want a passenger drop 208/241 case, your best bet is an 80's GM pickup/K5 Blazer/Suburban. Starting in the late 80's GM started to switch over to a driver side drop. Pickups were first in like 1988 I believe. The K5 lasted as a passenger drop through 1991 I think. Not sure about Suburbans. After 91, all GM full size vehicles were driver drop 241s.
To swap in a GM 208/241 to a Jeep transmission you just need a transmission to t-case adapter (to get the correct clocking of the case) and either an input shaft for the t-case or an output shaft for the transmission. You can get those all day at Novak or Advance Adapters. Swapping the input shaft on the t-case is far easier than the tail shaft of a transmission. But if the case is good and you need to rebuild the transmission anyway, the tail shaft option may be preferable.