I could use a breakdown on a 396 block I have,heres the #'s

casting- 3902406
cast date- j-18-6
stamped- T1201IV
vin-7R127238

what model car did this motor start life in?
Is the "R" in the vin a plant code?..and which one?
Also, the casting date and the stamping seem a little far apart..any Ideas why? work stoppage,pushed in the corner? or just not that many big blocks goin in that model??

Thanks

IV is a big car engine; suffix was used 65-68 for 396/325 auto.

R is Arlington, TX plant, which built full-size cars.

mid-October cast with a early December assembly is ok.