Transmission Replacement Question

[ALConfederate]

Mine is a 2001 with the 4R70W behind my 3.8. At 200,000 miles, I'm pretty sure the slushbox is history. From what I've been able to find out, the auto from& 01 to 03 cars is a direct drop-in, but the 04 unit will have speedo accuracy issues. Is there a fix for that or do I just need to go find a 01-03 unit?

TIA!

 

[wmburns]

The difference in the number of OSS teeth can be handled via re-programming just the same as a rear end gear ratio change.

However when considering a salvage yard unit why not just go with a "plug and play" unit?