Power steering gear box mounting bolts - 3 or 4?

[TheBMan]

I'm replacing the power steering gear box in my 72 Monte Carlo Custom. The frame has 3 mounting holes but the current gear box has 4 mounting points (see picture). I know that there are both 3 and 4 mounting point gear boxes but I don't know if it's normal for Monte Carlo's to come with a 4-mounting-point gear box? Or did they all come with the 3-mounting-point? I want to be sure to put the correct part on my car. Also, mine is 2.75 turns lock-to-lock if it matters.

Thanks!

[MC1of80]

You use 3 mounting bolts for the Monte. The boxes have 4 mounting areas for different applications. 

[TheBMan]

8 hours ago, MC1of80 said:

You use 3 mounting bolts for the Monte. The boxes have 4 mounting areas for different applications. 

I understand that you use just 3 mounting bolts (there are only 3 holes in the frame) but I'm wondering if Monte Carlo's came from the factory with gear boxes that had 4 mounting points despite using just 3 bolts. You can get the gear boxes both ways - 3 or 4 mounting points but the 3-point boxes are not nearly as common and are more expensive.

Like I said, I want to put the correct gear box in my car. If that means I pay more for the 3-point, that's fine. If these cars came with either the 3-point or 4-point gear box, I can use the 4-point, too.

[Dtret]

Run the part number on the gearbox and see what the application says it’s for. 

[MC1of80]

Yes they came with p/s boxes that have 4 mounting areas but use only 3. 

[TheBMan]

4 hours ago, Dtret said:

Run the part number on the gearbox and see what the application says it’s for. 

Thanks @Dtret. The part number on the casting, 5691676, doesn't tell you very much. Apparently that number was very generic as the internals could be just about anything. For sure I have the fast ratio 12.7:1 box (2.75 turns lock to lock).

I did read (and @MC1of80 confirmed) that these cars came with 4-point gear boxes even though they used just 3 bolts to mount. Given that my car is a numbers matching car, it's a good bet that this is the original steering gear box.

[71MonteCarloMD]

Good to know as I replaced the box on 72 C15 as it had 4 bolts.

[Scott S.]

These gearboxes were generic to lots of G.M. and Jeep vehicles. There's usually a painted two character code on the bottom end cover to denote what's inside. If it's lasted that long.