If the tranny is pre 95, you will have a lot of updates to do. All stock E4OD's 89-97 will have aluminum carriers unless they have been upgraded.
Starting from the rear. Reverse planet carrier. Toss it, replace it with a six pin steel part.
Low reverse frictions. You will find no stack clearance spec. You can get thicker steels or add more frictions and steels. You want to get this down around .20"-.40". This will get rid of the delayed reverse. You can go the easy route and use a shift kit. The kit will fix it too. I prefer both.
Center support. If it has a little bronz bushing (Pre 95). Toss it. Up grade to the bearing version (Post 95). While you have the center support out. Add a gasket available from Sonnax #36743G.
Change the forward planet to a six pin steel.
Change the overdrive planet to steel. This is a must. Get a new input shaft too.
Use a quality gasket set. Replace the sevo piston, if it has the snapring and plate. Toss them. The new servo will not need them.
Use new bearings, to do a better job. Replace the bushings.
Most important. Get a good Manual. ATSG is great and easy to get.
If you plan on building the tranny to extreme duty. You will need a F5 or better yet F8 pump. If you have the E9 pump. (Pre95) change it to the F5 anyways.