Originally Posted by Oldtruck1946
For the guys with the big trucks like 3/4 ton's and 1 ton's have short tubes that go as far as the support bearing and from there on its open drive. So there is no worry in changing out rearends to a newer 8 lug rearend with 3.73 gears instead of the stock 4.56 gears.

For AD trucks
Some (or all?) 3/4 tons have this half and half enclosed/open driveshaft arrangement.
All 1 tons have a completely open driveshaft, and 5.14 gears are normal.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-