Alan,
My understanding is that the standard rear end for task force trucks was a 3:90 for all transmissions except the overdrive which used a 4:11 ratio. It is quite evident as Packrat mentioned that it has a later transmission. The later trucks also used this short tailhousing from around 61 through 67 but it did not use a rear mount. This transmission has the the same gears as the long tail housing version. It is probably like most 50 year old vehicles and has been changed,updated, and modified as necessary to keep it on the road.
Fred
