This is a rare  carrier plate  that round pad is glued to on XK150, 3.4 saloon with early round paddisc brakes. I do not know if it is front or rear. Please inquire 1 954 JAGUARS , or 1 954 JAGPART .   Please look on my eBay store, Old English Motor Company. Contact me with your needs; I can put items in the store for you..Please note, overseas shipping is Priority Mail.Thank you, James Dean. thejaguru  Note, I am now located in charming Sebring, the Heart of Old Florida. Please give me exact model of transmission and year of vehicle.