Who makes/ made unimate cars.

I recently got a N scale BN ribbed 3 bay hopper in an ebay auction. It was not in its original box. The only identifying info on the car is the word UNIMATE and the date of 1989 on the bottom of the car. Who made this car? It looks similar to a Precision Masters car. Can someone please help me with this? I would greatly appreciate it.

Regards,
Whitney

Since I must be a Leper or something seeing as how no one responded, I contacted Red Caboose because this car looks similar to some Red Caboose / PM cars that I have already. Luckily a very kind gentleman named Bill McCung at Red Caboose told me the car I have was part of a 3 car set released in 1994.They kept all of the old PM records which was smart on their part. Just in case anyone is curious.

Regards,
Whitney