front springs and axles for 85 chevy 1/2 ton


Junior Member
I parted out 73 chevy for 7 1/2 western plow for my 85 1/2 ton, but am wondering what front springs to use. I have 3/4 ton camper special springs in rear (9 leaf), but I know 2 leaf in front need to go. What should I put in? I could use 3 leaf from 73 , but never drove truck (trans gone), not sure what shape they are in. If I buy new, should I get 3 or 5 leaf? Any hints on how much I might need to level the front with the big springs I have in rear? How about axles? 85 has 3.23 open, 73 has 3.08 posi with 12-bolt rear. Take posi units and put 3.42 gears on them? I never had plow before, so any input would be appreciated. All I need to plow is my own driveway, 300 feet long. Drivetrain is '72 350 with 700r4.

Alan Addict
I tend to think that either of the ratios you have is a bit too tall to use behind that overdrive tranny. I've had good luck with 3.73 behind the 700R4 and also with 3.08 behind a TH350. If you didn't have the overdrive, and since you're only working for yourself, I'd leave the 3.08 in and plow in low range. But, if you've gotta swap, I'd use the posi center section and go all the way up to 3.73

Chuck Smith

2000 Club Member
I agree with Alan. Leave the 3.08's in there, and plow in low. As far as the leafs, I'd get new 3 leaf units. Then again, you only plow your driveway, so I think I'd install the 3 leafs ones you already have. You can replace them next year if you need to. The 5 leaf, is overkill. I have a 77 Chevy K/20, and it had 3 leaf ones before I put in the lift kit. It's got a 8,400 GVWR, and the 9 leaf in the rear. I plow with an 80 GMC K/25, and it has 6 leafs in the rear, and 3 up front, with a 6,800 GVWR. It handles the Meyer plow I have fine. The Western is a little heavier, but the 3 leaf will handle it too.

Both my trucks have the same 10 bolt GM front axle the 1/2 tons use. Both my trucks have the TH 350 trans. Both my trucks have GM 14 bolt rear axles, with 4.11:1 axle gears. The mileage sucks, and the RPM's are high at 65 mph, but there is no lack of power, that's for sure!

Since you have a 73, and an 85, you might want to check out my website to learn more about them if you haven't already.



Junior Member
Thanks for feedback. Its kind of what I was thinking, put in 3 leafs and level it out with lift block. My wife, expecting end of January, already hates riding in it with just 2 in front! Those rear springs I have are amazing, I went to get gravel, waved the loader off when the tires started to squat, then went through the scales at 8000 lbs! It was getting close to bottoming the front, but the back was not even on the overloads. They are the long (57"?) 1 tons out of heavy 3/4, I think it rides better than my buddies 3/4 with the short springs. How much of that nice ride will I lose with 3 leafs in front? Luckily this is just my winter truck, I have 86 2wd for summer that I am getting ready to make a sleeper out of - going from 4.3 with 3 on the tree (last one made?) to 350 with 4 on the floor (New process overdrive out of 81 truck). Anyone ever plow with one of those manual shift 4spd overdrives? I think they call it out as 89MM.

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