12 Bolt Rear End ?? First Gen.

I am in the process of giving my 65 Panel a complete makeover. I plan to do some towing with it and I tend to load it up at times so would I be smart to upgrade to 12 bolt differential rather than rebuilding the 10 bolt?  Are they hard to find and will the 12 bolts from any other GM's be the same as the G10?  Thanks for the help, Jerry

10 is all u really need-unless ur drag racing ??????????????

The 1st gen 12 bolts came in 3:73s or 4:11s for ratios. While the center sections are different between the 10 and 12s. The size of the axles at the hub is the same. I am sure if you wanted to spend some money you could tame down those ratios in a 12 bolt but it sounds like it is much easier to play with ratios in a 10 bolt. I'm going with TP on this . The 10 bolt should be okay or no worse than a 12 bolt on load capacity. Now if you were going to adapt a real truck RA to the van you can gain in axle strength. But I know nothing about how that goes. Another thing , look at your GVW on the tag . There are recommended Max weights that your van is designed for. More weight equals more load on the stock braking and spring package.

My current diff is 10 bolt open and I plan on going to a 3:55 or 3:73 posi.  That plus the tires I want put me in the cruising RPM range I want to be in.  Are the 12 bolts difficult to find or will I save a lot of time and money by re-doing my existing unit.  I suppose finding someone with a spare 3:73 posi 12 bolt is just a pipe dream.  Thank you guys for all the guidance. Much appreciated, Jerry

,,,,,,VanAgain has a 3:73 in his van,,,,,,,,,,those will have 11-41 stamped on the ring gear,,,,,,,I see them around,,,,,,,,

Hey Jerry,

I've been wondering if I should swap out my 3.73 (12-bolt) for a 3.36.  I switched my tranny to a 700R4, which gives me lower first and second gears, so I don't really need the low-end help so much. I'll think it over.

Plus, I'll tell Leftcoast65 about this. One of us would be up for a swap with you.

I am not sure what my ratio is, the van came with a powerglide.  I will see if I can figure out the ratio this week.  Vanagain, with that trans combo any idea what kind of RPM you are running on the freeway?  Thanks Jerry

,,,,if it is 10 bolts, it is a 3:36,,,,,(says 11-37 on the ring gear),,,,now all those rear ends came in PosiTraction versions also,,,,,so you will find 6 different types of rear ends in a 1st gen.........

Well, the spin & count method confirms Donivans statement that it would be a 3.36. It is an open diff. If anyone in the area is willing to trade give me a PM and we will see if we can work out logistics.  Thanks  Jerry