Wow, that's cool!
They must have changed the waternecks on the later Mopar SBs. Funny, cause I measured this on my '92 360 van and it looked good, then I ordered a waterneck from PAW for an early SB, thinking they were the same, and of course it didn't fit, grrrr.
You can even buy those necks new from the parts store, I believe.
Thanks again, C-dog.
Lou