What rear brake caliper is this?

[CBA]

These are on my '74 but I'm thinking there are not original. Bought Poterfield replacement pads AP-31 R4-S for them as this is what I was told by the vendor fits but it does not. New pad on the left and old one on the right.

Thanks for any help

[Bill Verburg]

2.43" wide is correct for an M

I don't have the specs for an L but that's the only caliper that I know of which is smaller than an M

Just for information an A is ~3.02" wide

[CBA]

Thank you very much Bill. It looks like the vendor (Porterfield) put the wrong pads in the right box for my car. Trying to work it out with EBS..

[Flojo]

Just order the rear SC pads (1978-80) for M-caliper.

Someone obviously upgraded your 74

[Bill Verburg]

all 911 from at least '69 to '83 use the same rear M caliper and 20mm thick rotors
from '84-'89 the rotor was increased to 24mm, and the pistons were also increased in diameter from 38 to 42mm though still M sized case and the same pads(except that at some point which I'd need to look up the pads were equipped w/ wear warning capability

unless the rotors are 24mm there was no change

if the rotors are 24mm it's a downgrade because bias is ruined

[CBA]

Thank you Bill. Porterfield some how put the wrong pads in the box, they took care of it immediately and sent me the correct size I’m the size box no questions asked and picked up the incorrect ones. Excellent customer service. Greatly appreciated