[eschaider]

As I was looking at the before picture of the transmission Anthony posted in 141 (flip the picture to get the same orientation as the repaired unit) and the picture Fordfan posted in the picture bucket of the repaired unit, it appears that the countershaft third gear is not only misaligned but possibly narrower than the mainshaft gear.

I think the only way to determine this is actually measure the face width of the gear. Fordfan are you listening? It's easy to do on your unit, its already on the bench. If it is narrower then maybe it is not a TKO 600 countershaft!

Can a TKO 500 countershaft or a 3550 countershaft be put in a TKO 600 box? If it can and if that has happened here then the news is very good. That means a correctly engineered countershaft is already available. It is the one originally designed for the transmission and only needs to be swapped for the incorrect piece that currently is in there.

Ed