Chrome bumper 4-cylinder front: Spring eye and bolt tucked up behind the angle of the heel-board, front part of the bracket parallel to and close to the floor:

Chrome bumper V8 front: Spring eye and bolt below the line of the floor, the front part of the bracket is deeper and angles downwards slightly towards the rear so seemingly a bit lower than the CB 4-cylinder:

Rubber bumper V8 front: Spring eye and bolt even lower, the front part of the bracket is also deeper and angles downwards more towards the rear, and there is an integral reinforcing bracket around the eye of the spring:

The pre-77 Leyland Parts Catalogue only shows one part number per side for all cars, whereas it should show a different number for RB cars.

Chrome bumper 4-cylinder rear: Upper pin of the shackle goes through the middle of the chassis rail, and the bumper irons are curved over it. Note that these shackles are non-standard in that they have been extended:

Chrome bumper V8 rear: Exactly the same as for the 4-cylinder:

Rubber bumper V8 rear: Upper pin of the shackle goes through a bracket, which puts it at the lower face of the chassis rail. No bumper irons on a rubber bumper:

The Parts Catalogue has two GT side-members HZA3974/5 and HZA4924/5. The former is stated as being for use prior to HZA4924/5, the later one is stated as being for 4-cylinder chassis numbers 361001 on and V8 chassis number 2101 on, both of which are RB cars, indicating that only RB cars had the lowered rear mounting position.