a "NAPCO" was the 4x4 conversion, made up of modified corporate pieces, originally by a 3rd party, then taken in house - a NAPCO rear axle is just a GM rear axle, could have been used in anything, and as I said, wouldn't be a suprise if the rear axle used for the 4x4s was a posi and a slightly odd ratio .... if you can track those patent numbers [which may no longer be valid] you might find they were issued to the National Auto Parts Company

Bill [another 58 fleetside driver]

Moved over to the Passing Lane

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot