Early 60's to Mid 70's Racing Classes ( "stock" body )

Early 60's to Mid 70's Racing Classes ( "stock" body )

Is anyone here knowledgeable about the various stock-bodied racing classes from c.1960 - c.1976 ? I know there was :

- Super Stock
- F/X
- O/SS
- Stock ( e.g. , D-Stock )
- Modified Production
- S/FX
- Pro Stock ( '70 & later ? )
- ???

I'm building a couple of 1/25 scale race cars, and am wondering what class(es) they'd qualify for . If anyone has a rule book or any other literature they can share , that'd be great !
I know that some of these classes were super-strict , whereas some were more easy-going ( lots of grey areas ) .

Here's what I'm building :

- 1968 Hemi Dart : This one's going to be a GTS model with a crossram Hemi , T-Flite , Dana 60 . Full interior .
This is the new kit from Revell-Monogram ; it's based upon the '68 GTS / GSS , but has certain Hurst-Hemi parts included ( however , it has the GTS' upholstery pattern and door panels , instead of the 270 model's pattern ) .
I'm thinking Modified Production , but am not sure .

- 1969 Barracuda 383 : Old MPC-come-AMT kit , representing a "BH29H9B" car .
Stock 383 ( with power steering ) , 4 speed , 8.75 diff . Full interior .
C/Stock ?

Thanks much !