[rolling money pits]

Been looking at headers and got curious as to fitment across the two bodies. D ports only for this exercise.

Some brands break out 1st gen and 2nd gen Fs, along with early and late A bodies - 64-67/68-72.

Others have all F bodies under a single number, 67 - 81. Same for A’s, 64 - 72.

Yet another, Flowtech I believe, has one number for both, all years.

Since there’s only two engine mount styles, 2 or 3 bolt, and the exhaust ports/flange are the same, what makes one header year/body specific? I understand manual cars require certain considerations as does the backdrive linkage for auto cars. Some manufacturer’s list not manual, or need to modify the backdrive, brake combo valve interference etc.

What would prevent a header designed for say early 2nd gen F to fit in a 68-72 A chassis? Or vice versa? A 70 -72 A body could have either 2 or 3 bolt engine mounts whereas 2nd gen’s were 3 bolt only. Is it spacing from engine to floorpan, either vertical or front to rear from engine to firewall?

Thx

[geeteeohguy]

Suspension/A-arm location differences. IIRC, even the stock HO and log manifolds are vehicle specific due to headpipe location and downpipe fitment issues. They don't change over.

[Scott Stoneburg]

Steering box location

[rolling money pits]

Interesting. I’m not familiar with 1st gen F cars, is the box located behind the crossmember? My off the cuff memory of front/rear steer escapes me.

I checked again, the two flowtech ones I see on summit fit every chassis. I did read comments on how mounts had to be shimmed, but that could be collapsed engine cradles and squashed rubber mounts.

Rear lower A arm mounts are the ones in question, uppers shouldn’t matter? If the flowtechs “fit” all the cars it claims, they must have made concessions in tube location/routing?

[Scott Stoneburg]

1st gen has the steering box behind the cross member. It's right about even with the center ex ports.