It is my understanding with Saginaw P/S pumps, there are:
- SAE and Metric versions. All FMJ’s use the SAE version. The front wheel drive vehicles all use the Metric version. Pickups and vans used the SAE version until the either the Magnum engine or Hemi engine appeared. Metric pumps have “Metric” cast into the cast iron just behind the pulley and is viewable with pump off of the vehicle. I believe the "tin cans" will interchange between SAE and Metric pumps, but the mounting bolts and pulleys will not interchange – but don’t quote me on that.
- There are several different Chrysler “tin can” (I prefer to use the term can) versions. The (overall) “can” shapes are:
Oval neck (used on older Chryslers)
Teardrop neck (started usage in early ‘70’s). Oval and Teardrop cans will interchange providing the return tube and clocking is correct (or if tube position is compatible). Picture is located later in post.
Fender mounted reservoir (return hose goes to reservoir and large hose goes to pump can).
- Pulley design.
Older Saginaw pumps have a nut on end to retain the pulley. The older ones (all FMJ’s) use the newer press-on pulley.
Big blocks, small blocks and /6 all use different diameter pulleys as well as offset are generally different. Pulleys are easy to change out by renting a puller from an auto parts store.
The pulley on my '91 Caravan used a serpentine style plastic pulley.
- The routing of return hose:
These are the three can’s I’ve seen used on FMJ vehicles. There might be other designs, maybe.
Not sure which one is which, but I suspect one is for /6’s, another is for all small blocks without a cooler and the last is for those with P/S cooler (which attaches to the rear pump bracket double-sided bolts)
Note: Most Chrysler vehicles use 11/32” (8.73 mm) P/S return hose. All other car makes use a 3/8" hose.
- The location of pressure valve bolt hole and two bracket (double sided bolts) holes - determines the can clock position.
(see picture above, yellow and blue arrows).
Double sided bolts.
- There are a few different pressure valves used – which are interchangeable on all Saginaw pumps (not necessarily in order):
/6 pump (lowest pressure – best for road feel)
Normal
HP vehicles (340’s, Hemi, 383/440 Magnums, etc.)
¾ / 1-ton trucks/Heavy Duty usage (I think is the highest pressure – but lousy for road feel).
There are shims and different springs a person can use to modify the output pressure. I hadn’t practiced this to give any experience on it - but have friends who played around with pressures.
The same Saginaw P/S pump is used on my ’97 ¾ ton diesel pickup (with hydroboost) – but pump body is a bit different sense it piggybacks off the camshaft driven vacuum pump – but the can style is the same teardrop design (above). It is common for people to play with shims or to use a normal car pressure spring to get road feel more user friendly on pickups.
I hope this helps out some.
BudW