Given that Don Davis was involved with Groovesville, it wouldn't surprise me if it wasn't the guys originally at Stax, but some of the Grooveville boys. I think JT recorded at United Sound fairly often.
Interesting article here, don't know if it's been on here before.
https://www.freep.com/story/news/local/michigan/detroit/2016/05/09/detroit-united-sound-systems-forfeiture-i-94-drug-trafficking/84157598/