Early LaSalle Radiator Cap (need to identify)

[shammatt]

I have an early LaSalle (Cadillac) radiator cap that does not fit my 1932 LaSalle.  It looks correct visually, but the cap o.d. is too small.  I have borrowed an original 1932 cap (3-5/8" o.d. at the base) and it fit perfectly.  The cap I'm trying to identify is only 3-1/8" o.d. at the base.  It has the correct centerline ridge and 3-prong locking cup (I believe the locking cup is a newer replacement).  Most importantly the inside has the Stant emblem and address and the following part no. LS2457.

Anybody hazard a guess what year/model LaSalle this fits?
I'm trying to trade or sell my cap for the correct cap that will fit my LaSalle.

Thanks

[shammatt]

Through the assistance of a good Canadian friend and LaSalle owner, I've learned that the smaller radiator cap is for a 1931 (and I'd guess, 1930) LaSalle (and Cadillac?).  Anyway, with that knowledge, I need to go to the Buy/Sell/Trade forum to pursue my quest for the larger 1932 LaSalle.  Also, the 3 pronged locking cup that I recently purchased can be swapped for the correct 1931 two pronged cup.

[shammatt]

Now we have all the information (I hope).  The smaller cap on the left is a LaSalle cap.  It fits all models of LaSalle from 1927 to 1931.  It does not fit any Cadillac models.  In 1932, the LaSalle radiator cap (as illustrated on the right in the photo), shared the same larger cap size with all Cadillac V8s and V12s (1930-1932) and Cadillac V16s (1930-31).  I'm selling the 1927-'31 LaSalle cap and replacing it with the correct (and larger o.d.) version shown on the right in the photo.