Front Brake Shoes identification and fit.

[philwhitelaw]

Happy Friday everyone!  I have a collection of Triumph brake shoes which I need some help with.  The first shoes are just marked 1092, are 1 9/16 wide for an 8" drum, the linings are also marked 1092 Triumph.  Of the four shoes three are identical with the remaining one a mirror image to form a pair (i.e. put the shoes profile together and the cam and pivot faces are swapped over).  The same applies to the shoes marked W1074/5. Five are identical with one the mirror image.  My first question is why are the casting numbers the same for the 1092's?  Secondly, because the shoes are marked 1074/5 could these be fitted 180* to each other in a TLS drum? I ask this because some are additionally marked LM4 with possibly a T on the other side.
Thanks, Phil W.

[RDfella]

LM4 could be a reference to the type of alloy they're made from. Quite popular in the 60's / 70's.

[BSA_54A10]

Yep made thousands of tons of LM4 in the 70's
It is a heat treatable Al-Si alloy with up to 4% Cu
Generally used for gravity die casting.