69 C20 trailing arm rear end swap?

[FatherandSon]

The HO 52 4.10 rear end on my 69 C20 with trailing arms suspension is tired. What's my best option for a swap? Who has done one already? So far I have located a replacement HO 52 4.10 and a Dana 60 3.54 from a leaf suspension.
I also have a 12 bolt 3.73 posi from another project but the tube is smaller so I need some input for the easiest way to adapt it to the wider U-bolt holes formed into the trailing arms. I have a basic 350/290hp and TH400. I drive it daily but don't do much hauling since I lowered it 2 1/2 front & 4" rear.

Your input is appreciated!

[Benjamin]

I'm assuming that you have 8-lug in front and want to keep 8-lug in the rear. If so, the 12 bolt is probably not a good option. Also, I don't think there is a simple and SAFE way to make the small axle tube bolt-up to the C20 trailing arms without doing a fair amount of fabrication. Think spacers and shims all welded together. You could get some C10 trailing arms from the junkyard, but then you still have the mismatched front and rear wheel issue.

Do you want to change the gear ratio from 4.10 to 3.54? If you don't do any towing or drag racing then you would probably like the 3.54 better, as that will reduce your RPMs at cruising speed.

Now there is the task of mounting a leaf-spring axle in a trailing arm truck. A leaf spring axle almost certainly has the spring perches on the wrong side (top), so then you need to have new spring perches welded on the bottom. You might need a panhard bar mount welded on as well, I don't think a leaf spring truck has a panhard bar, where your trailing arm truck probably does.

Are you looking for a direct-fit bolt-in swap? I'm not clear if your "new" HO 52 is from a trailing arm truck. If so, then it couldn't be more simple, but then you wouldn't gain the advantage of the 3.54 gears.