History TROG racing numbers?

Hey guys,

I'm looking for some history about the racing numbers on the doors people used when racing back in the day. I noticed some have letters after the number and some just numbers.

Anyone know anything about it or where I can find some information?

 

Letters were used to ID engine size. Bob

 

Do you know what each letter signifies? I've seen C and B before.

 

Anyone else have any info?