Gentleman...it has been a while since I followed up. Here is what I came up with. Due to time constraints, (50-70 hour weeks) I was unable to do the work myself. After doing extensive research, and getting with several transmission shops here is the verdict: Per Matt at Allstar Transmission in Murfreesboro, TN.... The only difference between the pre 2000 RE4 transmissions is the valve bodies. The newer models have updated valve bodies and can handle more "abuse" due to significant improvements in orifice sizes, pressure, etc. It also addresses the reverse issue due to allowing the proper amount of fluid to get to where it needs to go due to the larger "veins" in the updated bodies. Per Mike at Future Transmission in Murfreesboro, TN.... He said the same thing. We also looked at a master kit from a 1995 RE4, and a 2003 Xterra RE4, side by side. Exactly the same, (even the clutches were the same size) with the exception of a letter designation at the end of the part numbers. So armed with this information, I opted to have Matt at Allstar rebuild one of my 1995 RE4's with a new updated valve body. Cost of parts: $1,345.00 (including new valve body and torque converter) Cost of labor: $455.00 Total cost: $1,800.00 with 12 month 12,000 mile warranty. Hoping to put this fresh rebuild in this coming weekend, if I do not get summoned into work... My conclusion: As far as I know to this point, the valve bodies are the only difference as stated before. The information about larger or beefier parts, I am going to say that honestly I could not see a difference. With the information posted by RJS about larger diameter internals, would not the master rebuild kits have to larger to accommodate? Just my thoughts...based solely on what I have seen to this point.