My 4-53T is 30 inches from clutch housing to radiator, not including electric fan, lots of room for fan. Firewall to radiator on '37 GMC(T-18 HD) is 40", that is why I Decided on T-18 plus adequate legroom, T-16 and smaller are for midgets.

A 6BT would fit in there, not in my plans,however.

Last edited by EdPruss; 12/26/2015 8:10 PM.
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.