Eliminator89 Posted September 9, 2007 Share Posted September 9, 2007 I have an '89 4.0 AX15 2wd swb MJ. Just bought an '88 MJ lwb 4.0 BA10 231. I am planning to install the BA10 tcase on a 4wd AX15. As I understand things, BA10 has 21 spline output, the AX15 (4wd) has 23. Can I swap the tcase 21 spline input with a 23 spline input? Know that I have not yet had a 231 apart and don't know the configuration for the input. Does the tranny output shaft slip into a gear in the tcase? If so, I'm thinking I can have a 23 spline gear installed when I have the tcase rebuilt. Also, the AX15 I have has the dreaded internal slave. I'll search here for info about changing to an external slave. Anyone have a link to this swap? Will I be able to use the '88 front driveshaft? Link to comment Share on other sites More sharing options...
oldjeep Posted September 9, 2007 Share Posted September 9, 2007 Yes, you can swap the inputs. There are a couple different length inputs used over the years but the 88 and 89 should use the same type. It's pretty easy to change the input. remove the 4 bolts from around the input bearing and remove the snap ring that holds the input shaft. Then you split the case and pull the input out of the planetary. Link to comment Share on other sites More sharing options...
Eliminator89 Posted September 9, 2007 Author Share Posted September 9, 2007 I don't have a 23 spline input for the '88 tcase. I'll have to get one. Anyone have one to sell? What I have is a recently purchased 4wd AX15 (unsure of the year but its from a 4.0 MJ) sitting in the garage and the '88 MJ that I have yet to get home. It'll be two weeks before I can begin tearing into the '88. I have to leave for Nebraska this Monday for two weeks of cellphone base equipment work. I'm going to have both, the tranny and the tcase rebuilt or do them myself before they go into my truck. If there aren't any expensive specialty tools needed for a rebuild, I'll do them with my brother's help. He's a bit more experienced than myself but I'm no newby to mechanics. I've never done a tcase but have done a simple manual tranny before. Anyway, not knowing what I'm doing has never stopped me before. We do have a nice shop available to work in. I also have the factory shop manuals for the truck including the AX15 supplement. They are just at the shop (60 miles away) right now so I can't look up some of the info I'm asking about here. Link to comment Share on other sites More sharing options...
oldjeep Posted September 9, 2007 Share Posted September 9, 2007 Probabaly easiest to just get a complete tcase. They are $75 at the local upull in rosemount. NP231 is simple to rebuild and requires no special tools. Link to comment Share on other sites More sharing options...
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