tranmission swap?

[judd77]

i have a 03 f650 with the 7.3 ad 5 spd allison can i put an allison 6 sp in? what are your thoughts on the 7.3 in the f650?

[oldbronco]

You might check with a Allison shop,a lot of the 5 speeds were just 6 speeds with 6th locked out. It just requires a programming change.
Mine doesn't shift into 6th until about 60 mph. 6th gear is normally a 0.63 ratio, so you might check to see if that ratio will take you out of the powerband for your truck. If it won't stay in 6th it's hardly worth havingthe work done.

John