I need help understanding exhaust donut gasket.

[rchavez101]

I recently installed a carbed 350 in my 94 that had a 4.3 liter. I purchased headers that were a replacment on a 5.7 liter for a 94. I am going to use my stock exhaust from the 4.3. I heard that it should bolt up to the V8. I went earlier to buy new exhaust donuts. The size they sold me fits good on the y pipe but it does not fit on the header. I am assuming that the donut lip should fit inside of the hole on the header? Is this correct. The donut is to big to fit in the hole. I never payed much attention how it would fit on the V6. Basiclly should the donut stay on the manifold/header and then you put the y pipe on then bolt it? Thanks in advance. Pics would be appreciated if you have them.