marine&hisvette

when I was yanking my engine out I had my brother take off the starter while I did other things..I went ahead and bought a new msd starter for the c6 and was hoping it would be plug and play since everything else on these cars are common sense.. the msd starter seems to come with shims and since the motor is in the car I can't measure it and was hoping someone here could help.. if they installed on did you shim your's? how should I hook the wires up as there's 3 posts on the msd and 2 on the stocker... also does the starter really have 3 grounds or just one and the otheres go to the block? the oem starter has a female plug as well and the msd doesn't. I read on ls1tech the msd diagram is wrong? please help