1956 Exhaust Manifold RH #3731558 Original???

[56 Vette]

I just purchased a right hand exhaust manifold for my 56, GM part #3731558. It does not have a date on the back side. The LH I have is dated. How can I tell if the RH is original or a newly manufactured part? Thanks for your help.

 

[1KULC7]

Orignals were part numbers for 1956 were:

Left hand 3725563....Right hand 3725563 First desgin

Left hand 3731557....Right hand 3731558 Second design, All Engines.

Exhaust manifold casting dates may not be visible when manifold is installed and some manifolds may not include a casting date. Casting date codes are as described on the engine block, except they don not normally cary a calendar-year reference.

Taken from NRCS Corvette Specificatin Guide....

 

[JohnZ]

If there's no date on the head side, it MAY be a reproduction (Paragon reproduces that manifold); however, the date can't be read when it's installed, and the reproduction manifold is less prone to cracking than the original was.