The offset is either 7/8 or 1". Can't find any with this big of an offset. Let me know if you have anything like this.
A quick learner from USA says:
August 11, 2017
This is a Grant roller system.
Paul from SWISCO responded:
August 16, 2017
Hello! Thanks for your question. Our 23-003 has a 3/4" offset with a 3/4" flat wheel that might work for your Grant door track. Please compare our measurements to yours and see if it's a match.