I am not a trans builder, just a DIY guy, much like yourself I am assuming. What I have done is a 5R55E rebuild that has gone (and still going) the 24 months/24,000 miles most outfits warranty for. So let's say so far I have SOME success. I have also successfully rebuilt & upgraded a 4L60E, and I am telling you the 5R55E is much easier to work on.
The bench work on a 5R55E is really not too bad.
Be super organized, lots of bins w/ lids, boxes, cable ties, AND LOTS OF DIGITAL PHOTOS. Have a large work area available. You need to do a complete tear-down and thorough cleaning.
Make sure the main case is good, checking for wear, particularly at servo bores, etc., and clean it out REAL good. Check the steels...you can tell if they are burnt, warped etc. Replace if necessary. The clutches have directional grooves, so get them back in the right way, and measure for the correct retaining ring once you have re-built each clutch pack.
Lip seals, make sure you tuck all of these properly, being careful not to damage them.
TEFLON seals: watch out for these especially, they are very difficult to work with...check the manual. There are several TEFLON seals on the turbine shaft, and re-sizing here is critical. If you snag one of those you are out of business, as they will be damaged. Manageable if you know it happened, as you can replace the seal and try again. But a disaster if you don't notice, as you could conceivably put the entire truck back together, only to have an immediate failure. Same thing on the end of the pump stator. Really ramp up your situational awareness when doing the TEFLONs.
Thrust washers: be very careful, noting the correct orientation of each one, and obviously replace at your discretion.
When you gut an assembly, i.e. clutch or gear-train, get a photo, and cable tie everything together as it comes out. While not foolproof, this goes a long way to keeping everything in the right place. Use a paint pen for marking bands, servo covers, etc.
Parking pawl: be very careful of how this goes. Check your bearings & sprags.
Valve body: update that...many good articles here on the forum.
Do your assembly air tests as per the manual...this assures you of proper assembly while still on the bench.
Pump alignment...critical, make sure to get this right. Also check the bushing in the bell housing, cheap to replace if have the drivers.
If you have 4x4, you will not be using the rear seal that probably comes in the kit...those are for RWD. For 4x4, have an extension housing to transfer case paper gasket on hand for your re-installation.
COOLER(S): clean these and their lines out real good. Very important. Use an inline magnetic filter downstream of the coolers. Contaminated coolers & lines are a major cause of recurring transmission problems. Torque converter will be replaced also.
Drain plug, definitely add one of these to your pan.
