How do you identify pre 74 SSI exchangers?

I have an old exhaust system and think I may have the pre 74 SSI heat exchangers but am not sure. Can they be identified by any part numbers or something?


Thanks,
Kenneth

Ken,

Just to clarify:
Pre-74 and SSI are two different things.
Factory pre-74 is either stainless or mild steel. SSI is a similar design mfg'd by Stainless Steel INC.

To ID that you have pre-74 style exchangers look for dual outlets coming straight back under the bumper and into a dual inlet muffler.

The difference lies in the fact that SSI's are true "equal length" systems. The factory's are close to equal, but not quite there.

There are no numbers on my SSI's, but one way you can tell if you have SSI's vs factory exchangers is by the ports for the allen nuts. The factory ones will have 6 (3 on each side) holes in the bottom for access to the allen nuts on the inner portion of the flanges to hold them on the studs. The SSI's are missing a couple of these. They had to eliminate them to make the systems "equal length"

Hope this helps.
Nick.

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Nick Shumaker
1982 911SC Coupe

Before 74 all exhausts on MFI cars, meaning S, E and 72 T, going back to the first MFI cars in '69, needed an extra fitting on the left heat shroud for ducting heat to the MFI. Cis cars don't need this fitting.