12 bolt 4 series carrier question

[SS69chevelle]

The heavy springs had me thinking it was a Moroso unit, I checked the gears and the clutches, it is 17-10 but the clutch count is 18 total the standard for the 4 series not like the brute strength unit which has 22 total. the only stamped numbers on the unit are the date C 13 J . There are COPO carrier gears 16-10 with the parts i got but i do not know if they would work in this unit or not since a COPO carrier is machined differently. I am trying to see if i can confirm if it is just a standard 4 series or a COPO one. I am beginning to think it is a standard unit rebuilt by moroso back in the day and never used. I was hoping someone here might be able to proide an example to compare to. thanks Andy