'74 Frame Rails
 

I'm needing to replace a small section of a frame rail on my '74 Trans Am. Does anyone know, are the '74 frame rails similar in some areas to the '70-73 rails or the later 2nd gen. frame rails or possibly a '74 only item? My assumption is that it depends on what part of the rails I'm needing. This is between the front spring mount area and the curve up in the front of the over the axle hump. Probably about 18" long from just behind the front spring mount thru the beginning of the curve upward. Thanks for any help on this question.

70-75 in general, after that they widened slightly for new cat exhaust requirement.

I didn't think about the catalytic converter altering the underbodies and possibly the frame in that area. If that's the case it would be '75 and up that would be different as the converters began is US cars at the beginning of the '75 model year. Since the trunks pans changed quite a bit in '74 and after, that makes me wonder if that's when they altered this forward portion of the frame. I just found a salvage yard seller that specializes in Camaros/Firebirds that said the forward section of the integrated frame is the same from '74-'81.

Yes, that should possibly be 74/75 chassis change, whenever the cat thing happened. Here's some more details.

http://transamcountry.com/community/...?topic=68213.0

thanks, good link!