1965 dart charger 273

Here is a fender tag decoder for 1965

http://www.1962to1965mopar.ornocar.org/ml-osterling65fendertag.html

Engine 31 : 273 4-barrel 235HP w/ Power Pak
Auto trans
Build date Nov 05 1964

I'll let Ulf do the sequence number.

Love the story of the 16 year old owner. 16 year old did not need a Hemi (well?)
Heard from a fellow this week telling me this week that he use to taunt the police with the original single un-baffled straight through Power Pak exhaust. Ulf had the story posted, I think, of a service man with a noise ticket due to the factory exhaust and turned it into the dealer.

Rear Axle (from blight.com):

There were only a few axle assemblies used by Mopar, and they are easy to identify. The names refer to the diameter of the ring gear in the differential.
7 1/4

This was the light-duty axle used in A-bodies and other slant-6 equipped cars. The identifying feature is that thedifferential cover is held on with 9 bolts.
8 3/4

All other cars used this axle. It's identified by the fact that the differential cover is not bolted on the back, but welded on and looks like a smooth bowl. The differential assembly comes out of the front as a complete unit, sometimes called a pig or a chunk.
8 1/4

This axle was not introduced until the late 60's, but sometimes you'll find them swapped into our cars. It can be identified by the 10 bolts holding the rear cover on.