The ta49 and te44 both have a 58mm compressor wheel ,i dont think there was a te-50, there was a ta-51 which was simular to a ta49 but a different bigger turbine wheel trim
I am only aware of its existence because I bought one 2nd hand on one of the forums. I ran it for couple years on my TR. As a practical matter, the only difference between the Myers' variant and the TE-44/TA-49 versions was in the exhaust wheel.
They all shared the same 58mm comp wheel as was pointed out above. The difference was in the hotside.
John Myers configured his TE-50 with a clipped H2(?) turbine wheel and he cut the exhaust housing to suit the larger turbine.
The TE-50 was more expensive than its TE-44 & TA-49 siblings due to the extra machina and balancing steps. I think that new back in 2005 they cost about $850ish.