5.3 Starter Issues

[steve aleve]

I am having issues with my 5.3 LS swap. I have a 54 Chevy 3100 and I have transplanted a 5.3 Vortec onto an S10 frame with a 4L60E. I bought a starter on CL and it makes a grind noise on start-up. The starter appears to be an 11 tooth reduction drive starter. When I shop online, I am seeing that the 2003 Silverado 1500 5.3 (what I have) is recommended to have a 9 tooth direct drive starter. Are these two interchangeable? Also, could this be a shim issue? Ans if so, how do I calculate how many shims to use?

Thanks in advance for all the help!!!