I bought a s/h Serow mount from the States and fitted it tonight. Unfortunately there are a few differences.
Firstly the two mounting holes have bonded in bushes that won't come out without ruining the mount - I tried hard
Secondly the angle of the mount is more acute than the TTRs which subsequently angles the speedo more. Haven't fitted the headlight yet but I hope it doesn't cause a problem.
So, if you buy a Serow mount for your TTR don't expect it to be a 100% fit
Anyways up, its all on the bike now so will see how the headlight fits tomorrow.