The printers code on the bottom flap at rear of Flip back laminated sleeve designates....
7001 TPS Printed and made by Garrod & Lofthouse Ltd. Patent No. 943695 STML 11133 - not certain of the exact patent number.
By using the album printers code "7001" = Jan 1970, it is noted that the album release date has been entered as 1969, that might be because the album has ℗ 1969 on the labels, or that the sleeve is a reprint of an earlier 1969 issue, due to selling out first batch.
I am confident of a January 1970 release, but eventually, a date will emerge, (New Singles listings, which did carry album issues as well, although not sure about as late as1970).
According to that excellent website "Don't Forget The Motor City", this album was first released in US on Gordy S949 on 23-Sep-69, based upon the fact that one of the tracks B6 "Slave" was recorded and completed 13-May-69. (when finding link, please scroll down the page.)