I recently purchased a 396 casting code 3855961 which I find to be a 1965-66. My problem is the stamp pad numbers! They read T122IIVR. Now I could be mistaking one of the I's to be a 1, but I find IV suffix codes to be correct for a 1965, but don't find any suffix codes ending VR? Any help here would be greatly appreciated! I have referred to nastyz.com & 1953-1975 Chevrolet book of numbers with no results. Thanks for your help!
Randy  

Hmm, I'm wondering if the VR suffix has something to do with your motor being a factory replacement engine? I'll have to do some digging and find out.  

Ok. Talked to Chevy expert and historian Doug Marion (former editor of Super Chevy, and one of the greatest guys in the Bowtie universe!). Here's what he had to say about your motor:

1965 396 325 hp Impala: There is an "IV" code for the L34, 325 hp 396, TH400.  I will assume this includes a Quadrajet carb.
There is also an "IVR" and "IVH" for the same engine/trans.
IVR = Rochester Quadrajet carb
IVH = Holley Spreadbore carb

I  don't ever recall seeing a Holley carb  on a '65 325 hp 396.
The 325 hp cast iron intake manifold was a spreadbore-type so the carb had to be the same.  
It would be interesting to see what Holley records indicate.

The only Holley I've seen on 396s is the square bore 360 hp (oval port/hyd cam) and the 800 cfm dual inlet (375 hp/rectangle port/mechanical cam).  

Hi All,

Just to clarify, I have a 1965 Impala SS with the 396 / 325 HP. It did come with the Holly single pumper. I believe the NOS was a 550CFM. I replaced it with a 750CFM some years ago. Just writing to verify that come of these cars did come with the Hollys.