Swapping diffs on high boy
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Cross-Country
Joined: Sep 2012
Posts: 58
Likes: 12
From: shuswap lake
Swapping diffs on high boy
Hello all, I have the opportunity to buy a 75 highboy, it of course has the low pinion closed knuckle 44, in the shop I have a completely gone through high pinion Dana 44 from a 79, just wondering if a guy swaps in the the HP axle does it negatively affect the pinion angles with the divorces t case? Does it clear the oil pan? I know I got switch the brake distribution valve for the discs, I gotta spare hanging out here, I know some one here has had to have done it before, just trying to make a plan
Laughing Gas
Joined: Jan 2012
Posts: 887
Likes: 70
From: Santa Clarita
I did a 75 highboy low pinion closed knuckle D60 to 78/79 high pinion D60 swap. I run a 4" lift. Oil plan clearance was not a problem. I didn't measure pinion angles, just out with the old in with the new and 'measured' by driving the truck. Driving it felt the same. No binding or new vibrations so I called it good. 
I changed my brake proportioning valve, new brake lines/hoses, different pitman arm, & added crossover steering, (I also swapped to 78/79 power steering)
HTH
I changed my brake proportioning valve, new brake lines/hoses, different pitman arm, & added crossover steering, (I also swapped to 78/79 power steering)
HTH
Thread Starter
|
Cross-Country
Joined: Sep 2012
Posts: 58
Likes: 12
From: shuswap lake
I did a 75 highboy low pinion closed knuckle D60 to 78/79 high pinion D60 swap. I run a 4" lift. Oil plan clearance was not a problem. I didn't measure pinion angles, just out with the old in with the new and 'measured' by driving the truck. Driving it felt the same. No binding or new vibrations so I called it good.
I changed my brake proportioning valve, new brake lines/hoses, different pitman arm, & added crossover steering, (I also swapped to 78/79 power steering)
HTH
I changed my brake proportioning valve, new brake lines/hoses, different pitman arm, & added crossover steering, (I also swapped to 78/79 power steering)
HTH
Laughing Gas
Joined: Jan 2014
Posts: 1,076
Likes: 500
From: Kenai
I put a 79 high pinion D44 from a F250 into my 75 highboy, along witht he 79 power steering box. No lift. I cleared the exhaust and oil pan no problem with the drive shaft. I did change the yoke on my drive shaft (old one was wore out), but it seemd to be a very similiar length to the original. I have also added an astrovan hydroboost and master cylinder for disk/drum..I haven't driven it yet as its still a work in progress. Hopefully it will all work!
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