5 star makes a steel body impala body,iam thinking you just might be seeing one of these, this year at one of your local race tracks that allow any steel body as per the rule 😉 😉 😉

Chevrolet >  Impala >  Straight-Up Steel (older style Late Model Stock)
Straight-Up Steel (older style Late Model Stock)
These older style straight-up steel Impala body panels are available on a limited basis, while stock lasts. We recommend that our customers running these bodies update to the new Late Model Stock (LMSC) Impala

Here is Sunset's body rule.

·        Body must be steel and stock in appearance to the original vehicle. 

·        Tires must be inside fenders & scrub rails. 

·        Bodies may be interchanged between make and model

Here is Sunset's body rule.

·         Body must be steel and stock in appearance to the original vehicle. 

·         Tires must be inside fenders & scrub rails.   

·         Bodies may be interchanged between make and model

How do rule 1 and rule 3 work together? Do you have a common chassis spec? Does the engine make have to match the body?
With rule two are there body templates? Making a car wider or the scrub rail fat doesn't seem like it would be a problem to me.

1&3 do work together...Its like you could put a stock body of 97 monte on a '85 rear wheel drive frame. In the south allot of tracks are allowing the use of stock FWD bodies on Stock RWD chassis