MCI5 Series, repower?

[luvrbus]

It is just the back of 654 that is longer a different tail section lets a 654 work in place of the 644 and allows for 11 1/2 in drive shaft you can also change to a SAE 2 bell housing and do away with the drop ring and spacer to allow for a longer drive shaft fwiw 

They have torque converters now for the 644 that will allow up to 1100 lbs of torque the gears and clutches were not the weak link it was the converters on the 600 series   

good luck