1990 automatic tranny

[deesenuts]

What auto tranny came behind the Cummins in 1990. I need to find a way to convert it to 4wd and find a tcase. Any help would be greatly appreciated. Thanks.

 

[ldebrois]

These came with a 518 and you need a 23 spline input shaft on your NP203 T- case.

 

[crashnzuk]

90 would have a 727, not a 518. The overdrive didn't come until mid 91 when the trucks were intercooled. Cummins trucks came with an NP205, you don't want an NP203 unless you want a full-time case. You could find a 4wd 727 tailshaft and housing that will bolt to what ever t-case you want to use. I have heard of several guys using NP208s with good luck, unless you have a dislike for chain drive aluminum t-cases. Talk to a transmission shop, I bet they could help with the trans conversion.
Travis..

 

[ldebrois]

I forgot about that, sorry
Lee

 

[motorgod7]

how hard is it to change over to a 518? my 727 takes a min to spool up before the truck moves, was thinking a 518 would be worthwhile upgrade.

 

[crashnzuk]

how hard is it to change over to a 518? my 727 takes a min to spool up before the truck moves, was thinking a 518 would be worthwhile upgrade.

Are you talking about when you first fire it up? If so, that is 100% normal for a mopar trans. They don't circulate oil in park, so if you want it to go directly into gear, you have to put it in neutral before you start it or at least before you select a range. If you want O/D, do the swap. Never done the swap myself, so I can't speak to the dificulty there.
Travis..

 

[motorgod7]

tks Travis, yes it only does this after its sat for awhile. Other than that it seems fine. I'll try the nuetral trick from now on, w/both my mopars.