M1009 replacement 12 bolt rear

[2deuce]

My 10 bolt rear is bad, and I found a 12 bolt from a late 70's pickup(1977 I believe). It has a 14/43 tooth count. Practically the same as the 10 bolt 13/40 count. Will I have any problems with u-joints, and driveline length? Are the perches in the same spot as the M1009? Emergency brake cables the same? Anybody done it? Thanks

 

[Barrman]

How often do you plan to be in 4x4? That is the only time the ratio between the front and rear matters. If you are always on loose surfaces then it won’t matter at all as close as the numbers are.

 

[2deuce]

How often do you plan to be in 4x4? That is the only time the ratio between the front and rear matters. If you are always on loose surfaces then it won’t matter at all as close as the numbers are.

The only time on the road that I would be in 4x4 would be if it's snowing. I'm wondering if the rear would push the front? In the past it was very capable on a snowy road.
Is it a direct swap? Driveline work is expensive around here. Thanks

 

[Barrman]

If you are paying someone to do this swap then I am sure they will find things that don’t match up and require more time and money to make correct. With that in mind there are people on this site and around the internet with NOS brand new still in the crate M1009 rear axles that can be bought for not really all that much money. Shipping is the killer on those deals.

The U-joint might be the same size but I am pretty sure the way it attaches to the rear axle will be different.

The parking brake cables should be the same.

So should the brake hose attachment to the brake lines.

I would suggest new U-bolts for the axle to leaf spring connection.

Again, if you won’t be doing the work yourself. This could get real expensive real fast.

 

[2deuce]

I will be doing the job, so I won't have that expense, but any driveline work would need to be farmed out. I've read that the pinion shaft is different, but I don't know if there are crossover u-joint parts that work for both. I'm going to call around to some driveline shops to find out if something inexpensive will work. I found a cheap 12 bolt, but want to make sure it doesn't become costly. If I do attempt this swap, I'll report any problems. Somebody else could buy it, if I don't make up my mind soon. Thanks

 

[Valley Rock]

The ratios are the same .

If the spring pad width and wms to wms (wheel mount surface) are the same, then you're in business .

The u-joint and e-brake cables are minor and most likely the same, crossover joints are common .

The tape measure is your friend .