IDI for life
TBH, couldnt tell what the difference is between a 9 and 10. We have a 85 GMC brigadier with a Detroit 2stroke, and i believe a 9 speed, shifts beautiful. Also a 93 F-800 with the 505CID Chummins. Eaton tranny, all i can remember same shift pattern, a little tight, but only has 26k miles on it. Wouldnt mind either one in my pickup. Probably lean towards the 93 as it has a shorter throws.