I have a 12 bolt posi Corvette center section with 5:13 gears. It needs axles (they were lost but Tom's 1480 axle kit comes with them and you would want that kit anyway) and a rear cover. It was used briefly but it looks new inside. I spoke to Tom and he said that I could use any of the Corvette 12 bolt gears that he currently offers (3.73-4.33). A rear cover is $130 and gears are around $340. This was purchased as a spare unit but they are so durable that I'll probably never use it. ....................Sold.................... Thanks.