1950 Chevy wiper motor compatibility on 1990 Chevrolet 1500 Pickup

Please forgive the inaccurate year above, no earlier model options were provided. I'm rebuilding a 1950 Chevy Truck, with 12 volt conversion. I would like to save a few bucks by installing a compatible motor from another car/model rather than pay for the replacements marketed for this switch. What do I need to look for in finding a compatible motor?

Asked by for the 1990 Chevrolet 1500 Pickup
If anyone knows it would be Bill at Valley Auto Supply in San Francisco 415-239-5880 he's been selling auto parts for 50 years