4l80e doubler question

[broc944]

I am getting things around for a doubler behind a 4l80e in my Sub, I have done a search on this subject and really do not get a clear pitcure on what needs to be done to bolt the 203 range box to the tranny. Do I drill and tap the range box itself or do I use a adapter plate and re drill that, and if so which one.

 

[afroman006]

I believe you need the same 32 spline input for a TH400. I know 4L80E adapters have the common round 6 bolt pattern on the t-case so unless you happen to have a 203 with this pattern (I dont know if they ever came with it), you will have to drill and tap the actual face of the case. Its thick steel so I wouldnt worry about doing it, plus you can clock it however you want while you're at it.

 

[big83chevy4x4]

you can also use a th400/np203 adapter, but you need to get a spacer made up to account for the output shaft length difference.

 

[broc944]

So the drilling tapping method would be the best way to go then?, and if so do I drill straight through the case, and tape or dope the bolt threads so they do not leak?

 

[sweetk30]

i have talked to ord on this and the best is 4l80 adaptor to the 6 bolt and drill/tap range box as you want it.