hi, the ecu's for all 90 tdi, 110 tdi, 100 tdi pd, 115 and 130 tdi pd's are different. also all 90 tdi us cars have different ecu's than the european 90 tdi's.
beside the ecu, there are also differnces in the engine, turbocharger etc between the 90, 110 and 115 models. hope this helps