I found the thread about converting from an I6 to a V8 but I didn't see my question answered. The car I bought was an I6 and I am putting a 302 in it. I already did a complete suspension change to handle a small block V8. I know it was mentioned that a 68 is easier to convert but will my rear axle hold up? I was planning on changing the rearend gears to 3.73s but should I change the whole thing? What size axle comes in the 68 I6? I have tried to google it but all the websites that mention specs on this car were about engines. I have no idea if a V8 was ever put in it because the entire engine bay was empty when I bought it, except for a master cylinder and steering box. Thanks in advance

 

To tell if the car had a 6 in it look at the VIN and if the fifth digit is a T then it was a 6, anything else was an 8. To tell about your rear axle, four lugs is an 8", 5 lugs is a 9". It is possible to change the axles and build a 8" to take up to 300 horsepower but its very easy to find a 9" and spend about the same amount and have a stronger differential.

 

No 4 lug is a 7.5 5 lug is 8 inch and 9 inch.And yes if its a 7.5 you need to change it out to a 8 inch at least.

 

You need at least an 8 inch rear end. It will be fine for most V8 applications. Like andrew said though 4 lug is 7.5, 5 lug is 8 or 9 inch.

 

thanks guys, that helps a ton