3/4 to 1/2 ton switch

[longhorn69]

so i have a 69 longhorn. i have already swapped my front end over to half ton hubs with the conversion spindles, and now it's time to swap the rear end out. just wondering what i should be looking for when i pick up a 1/2 ton rear end. i know it should be pre 86? and 2wd. can i just grab any rear end and it will fit? also, should i swap the 1/2 leaf springs in for the 3/4 ton ones? i dropped the front 3 1/2 in, so the back will need to be dropped 5 in or so, and i will be wanting to put a disc brake kit on the back. any help i can get is appreciated, i want to get this truck rolling!

[Longhorn Man]

welcome to the insanity.
I'll move this off the engine and drive train page, and put it on the main truck board.

[lpaine]

The rear trac-bar & bracket is different(on the frame) you'll need to take the 3/4 ton bracket out (drilling and/or grinding rivets out, yeah) and swap in the 1/2 ton bracket/trac bar(more drilling and grinding) also the brake lines and hoses may be a different size, 3/16" for 1/2 ton and 1/4" for 3/4 ton I beleive.

[crazy longhorn]

What I did on mine......I used a 75 -12bolt axle, flipped over top of the springs. The stock leafs were brought down to a 4 leaf, by discarding the flat helper & bottom 3 leafs. this actually set the truck too low , so the spring hangers were removed from the frame, & moved downward to lift it back up a tad. I used grade 8 -7/16" bolts & pinchloc nuts on the assy. This worked out to be a 5-5 1/2" drop(cheap, but labor intensive). The spring saddles on the 75 diff dont line up with the longhorn spring centers, so you need to cut them off, & use aftermarket saddles(Direct connection pcs work), & have the U bolts & plates made up. crazyL

[Hart_Rod]

Originally Posted by lpaine

The rear trac-bar & bracket is different(on the frame) you'll need to take the 3/4 ton bracket out (drilling and/or grinding rivets out, yeah) and swap in the 1/2 ton bracket/trac bar(more drilling and grinding) also the brake lines and hoses may be a different size, 3/16" for 1/2 ton and 1/4" for 3/4 ton I beleive.

What's different? I replaced the 1/2 frame of my suburban with a 3/4T frame and other than some extra bracing on the rear, I didn't see any difference. Did I miss something?

[longhorn69]

Originally Posted by crazy longhorn

What I did on mine......I used a 75 -12bolt axle, flipped over top of the springs. The stock leafs were brought down to a 4 leaf, by discarding the flat helper & bottom 3 leafs. this actually set the truck too low , so the spring hangers were removed from the frame, & moved downward to lift it back up a tad. I used grade 8 -7/16" bolts & pinchloc nuts on the assy. This worked out to be a 5-5 1/2" drop(cheap, but labor intensive). The spring saddles on the 75 diff dont line up with the longhorn spring centers, so you need to cut them off, & use aftermarket saddles(Direct connection pcs work), & have the U bolts & plates made up. crazyL

and those were the longhorn springs you used? do you think if i dropped the flat helper and bottom 2 springs it would achieve the same drop with out having to move the spring hangers? do you have any pics of your truck? i'd love to see a dropped longhorn!

[crazy longhorn]

Go www.webshots .com, look for hotrodhorn.....if you need a password, type in MuFFy. I sure cant answer your ? on the rear springs(havent tryed it) That old truck bites.....I sure spilled some blood, & had several "theads" in my knuckles over all that was done....crazyL

[longhorn69]

Originally Posted by crazy longhorn

Go www.webshots .com, look for hotrodhorn.....if you need a password, type in MuFFy. I sure cant answer your ? on the rear springs(havent tryed it) That old truck bites.....I sure spilled some blood, & had several "theads" in my knuckles over all that was done....crazyL

did you have any problems with the drive shaft bolting up to the new rear end?

[crazy longhorn]

The shaft was custom built at a local driveline shop, but there were many mods in the driveline, including eng position. The I6 stands gave 3 1/2" of set back, so neither end was stock lenght. You will probably need to have the rear shaft shortened, set up the proper U joint, & balance as a complete assy. Once you change 1 part, it all seems to "snowball" from there......crazyL