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Discussion Starter #1
What are the differences between the various hydroboosts available for the GM vehicles. Will they interchange? Not that I would want to buy it from the dealer, but there is hundreds of dollars of difference between them depending on the VIN according to them. P/S ports different, amount of assist provided, bolt patterns, what?
 

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Mulling over the years, there seems to be at least two "strengths". The lighter trucks (1/2 and LD 3/4-ton) got a unit with a 0.60" diameter piston, and heavier trucks (HD 3/4-ton and 1-ton) got a 0.78" piston.

Then you have monsters like the 3500HD and P30 (P40?) walk-in vans with 10-lug wheels & 4-wheel discs. I don't know the piston size on these, but I know the master cylinder from these won't physically bolt up to a lighter boosters - it may be larger again.

Depending on the chassis-type the unit is installed on, the firewall mounting plate and pedal rod varies. Both can be changed easily. The plate is either threaded on or retained by a snap-ring. The pedal rod is only retained by a slight crimp - you can pull the rod out, and install again by re-crimping.
 

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Discussion Starter #3
It's on a '93 HD 3/4 ton Suburban with a 454 and 14 bolt rear (8 lug).
So, any booster out of a HD 3/4 or 1 ton throughout the years should be the same? It's leaking pretty good and I tried a seal kit with no luck.
 

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That is the 1-ton spec version... Anything with 8-lug wheels in the same body style (88-98) should physically bolt to your firewall and have the same amount of assist.

This one's off a 95 1-ton. You tell me if its the same:

 

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Discussion Starter #8
That does look like mine. I looked at the above sites and they break it down to 2500 8 lug, or 3500 drum, or 3500 disk rear.
 

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Discussion Starter #9
That does look like mine. I looked at the above sites and they break it down to 2500 8 lug, or 3500 drum, or 3500 disk rear.
 

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Originally posted by deuce:
<STRONG>I looked at the above sites and they break it down to 2500 8 lug, or 3500 drum, or 3500 disk rear.</STRONG>
I know... its deceiving. The 2500 8-lug and 3500 drum are one and the same. The 3500 disc is different. You'll notice you get the exact same hits when you look up those two.

What you see on those websites is a condensed "web-version" of software that most auto wreckers use. I'm on the inside, I know the scoop <IMG SRC="smilies/biggrin.gif" border="0">
 

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Discussion Starter #11
Just curious, what's the difference between the disc version and the drum version hydroboost?
 
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