6 Lug to 5 Lug Conversion

[425HP409]

What is the best/easiest way to convert the rear of a 70 1/2 ton to 5 lug?

[hevy_chevy67]

I would try and find a complete 71-72 rear end and swap it, personally. I like the 71-72 rear end as its wider and will already have 5 bolt axles.

If not, CPP sells 5 lug axles you could swap in. Being that your truck is a 70 though you will have to be careful which ones you order as half way through 70 they changed to wider rear end housing. They have 67-70 5 lug axles and 71-72 5 lug axles.

[Peanut74]

When I converted my '67 rear end to 5 lug I used a Yukon conversion kit. The kit number is YA G6569 RACK and was just under $400. It came with 5 lug drums and the axles.

[Palf70Step]

70s. Most have the wider rear end as71 to 87. I just pulled my old axles and slid innew ones. Brakes are the same except for drums. Early made 70s had the narrower rear axle like 69 a older. I have vernier hear exactly when the crossover was in 70, but I really don't think yhe narrow ones were used for very long.

[dmjlambert]

This was my journey to conversion on my 1969 C10 with 12 bolt differential, including measuring which axle length to determine what length axle shaft to get and discussion of options and brands.
https://67-72chevytrucks.com/vboard/...17#post9040817

I was pleased with the Motive Gear axles I bought from National Drivetrain. They were cheap at Summit and National Drivetrain's website, cheaper on Amazon, and cheaper yet on National Drivetrain's eBay listing. My 1969 had the shorter axle and was Motive Gear part number MG6569. If you have the shorter axle then that is probably what you need. If you have the longer axle then Motive Gear's part number appears to be 14071751 for a 12 bolt differential.

Peanut74 talking about Yukon's kit also sounds very good. Since that's a 1967 it should be the short axle. So measure and see what you need since they supposedly had either of the 2 possible axle widths in 1970.

I suggest use heat when removing the pinion shaft lock bolt. Apparently they are common to break. I'm not sure if it is recommended to replace them even if not broken, as I had to replace mine anyway. It is unpleasant when they break, but fixable if you proceed with care and patience. https://67-72chevytrucks.com/vboard/...d.php?t=841065

[uncle]

Not trying to step on any toes but I believe the 12 bolt axle ended in 81 not 87.

[Palf70Step]

You could get both, but the 10 bolt became the standard axle, especially on 6 banger trucks. My 81 (250) and 83 (305) both had 12 bolts. Not sure what the rhyme or reason was on which one came in them.

[CC69Rat]

Early housing is 55.5" long measuring from the inside edge of one backing plate over to the other side in the same spot. The later housing will be 57" plate to plate.

I have seen both in 70 model trucks. It can still be 57" housing and 6 lug, but I've never seen a 55.5" that was 5 lug (factory) But 70 was the conversion year. I think maybe they just used up the early housings in the early 70 build date trucks and switched over for the mid - late year built 70s. But either width they'd still be 6 lug.

I personally like the narrow housings, as it allows for less wheel backspacing.