Identifying 3rd member

[TexanKen]

I need some technical guidance on identifying the rear end :bootysha:i n my '72 Duster. When I purchased it last summer I took the seller's word it was an 8 3/4" Mopar unit. Recently a mechanic friend was checking for a fuel leak and told me it was an 8 1/4 not 8 3/4. Never having heard of an 8 1/4 I have no idea how I can determine who's right. Any guidance on some quick way :angry7: to identify this rear end?

 

[thanson_mopar]

I need some technical guidance on identifying the rear end :bootysha:i n my '72 Duster. When I purchased it last summer I took the seller's word it was an 8 3/4" Mopar unit. Recently a mechanic friend was checking for a fuel leak and told me it was an 8 1/4 not 8 3/4. Never having heard of an 8 1/4 I have no idea how I can determine who's right. Any guidance on some quick way :angry7: to identify this rear end?

does it have a 3rd member come out of the front? if yes than its a 8.75. If it has a cover on the rear of the rear end than count the number of bolts to see if its a 7.25 or 8.25