My rears (one anyway) decided to puke brake fluid, so, apart they came, cleaned up nicely, ordered kits.
Odd, the outfit I ordered from said 1-1/2".....mine measures 1-9/16", and has that size in the raised casting letters.

I have new 1.5" calipers enroute, should arrive by courier today, but, anybody know when they uses 1-9/16" rear calipers?
All 4 halves are the same.

1964 MK2, 2.4L, RHD, 118XXX

Thanks.

 

Sorry, I can't be much of any help but you can contact
www.britishparts.co.uk , those guys sell classic parts and surely know better

 

WIth a car that old, the pistons could well have already been replaced and by somebody who did not realise the importance of the diameter of the pistons, so just bought parts that successfully bolted-on without looking at the dimensions.

I remember replacing all 8 piston assemblies on a Mark 2 2.4 in the '80s, and managed to get them free from a chap who worked for Lucas, who owned Girling at that time. A quick look on the SNGBarrat website shows the fronts are 2 & 1/8", and the rears 1 & 1/5", so you are right. Where the ones you took off came from I don't know, maybe another Jaguar model like an S-Type or a Mark 10. These are different part numbers, but the size is not given.