Greetings from San Marcos, Texas! I just picked up a 1992 rolling project that has had some motor work done. It is a 350 TPI with aluminum heads but the heads have no casting numbers under the valve covers and they are unbranded, nothing marked on the front/rear machines faces with accessory bolt holes. They have 1.45” dual springs, angled gasket-seat plugs, 3/8” screw-in studs, no exhaust crossover, and accept both center and perimeter valve covers. The diver side head is stamped with 0803-0130 above #7 exhaust port, passenger head is stamped 0803-1730 above #2 exhaust port. Any ideas? Thanks!

Old pro comps maybe? I searched 0803 sbc head and procomps came up a couple times using 0803 as a section of the part number. Purely speculation.

Probably some inexpensive offshore aftermarket heads.

Looks like Patriot heads, only ones I've seen with those lines cast in the valvecover area.

Patriots seem likely
post 33 and 34 to compare pictures
https://www.thirdgen.org/forums/afte...iot-heads.html

Thank you all for the feedback! You gave me some good intel to act on. Unfortunately, the mystery lives on. Here is what I found so far:

1. Patriot - I reached out to ProMaxx (who purchased Patriot Performance and Alabama Cylinder Head Exchange) but they do not have a catalog of legacy part numbers. In any case, they assured me that Patriot marked the ends of their heads (CNC engraving or laser marking) since Day #1. If my heads are Patriot, they somehow skipped this process. Maybe defect heads sold at discount. (Super.)
2. ProComp - I reached out to RHS who supposedly bought ProComp. They did not. They bought Pro Topline out of New Zealand. They couldn't help. ProComp itself does not have a website. It seems they dissolved?
3. Liberty - ProMaxx recommended to investigate Liberty. No match for part numbers or castings/features. My heads are not from Liberty.
4. Summit - Summit also lacks catalogs for legacy Patriot or ProComp head part numbers. These heads could be 10 years old, or older. Do you know anyone who might have catalogs / part numbers for old Patriot or ProComp heads? An engine service/machine shop or...?

Thanks again for all your help! If I can't solve this in the next 2 weeks, I will let it die.