I got a line on a TH700R4 but I need to identify the year. The guy selling it says it's a TH400 from a 1990 Camaro but it is a 700R4 (I let the guy think it's a 400, he's a real A--hole and wants $400) but I need a way to id the year as the 1988 and up are preferable to the earlier units. It has the 4-pin plug so I know it needs a lockup converter. The trans fluid is clear and smells ok. Can anyone tell me how to positively identify the year it was made and any other tips to acess condition?