If you are going with R134 you need to start researching this. Good to have all new parts, that way you can begin with fresh R134 and it's correct type of oil. Best if you can find a compressor for your car that is designed for R134. I bought a digital postal scale on Epay for like $20 and I add only the correct amount of freon. Your car came with a spec for how many pounds/ounces of R12. The correct amount of R134 will be different because they are different gasses. Pro's know how to adjust the amounts for equivalent cooling and that info can be found on the net. Read up on this at the HVAC sites, "how to convert R12 to R134". The method of adding freon slowly and watching a thermometer jammed in a duct works, but is crude and you can overcharge the system causing damage. The reason the system needs to be vacuumed down with a good pump is: 1- to test for leaks. If it holds 29" vacuum for an hour with the pump off, probably no leaks. 2- water boils at 29" vacuum so you are boiling any moisture out of the system before adding the R134. Hoses are different too- R134 may leak through old style hoses. R134 hoses have a teflon liner. My AC leaked badly but I felt all this was too much trouble so I just acquired a used rebuilt compressor, new accumulator, and new orifice for my wagon and filled it with an R12 substitute called ES12. I was able to keep the same mineral oil and fill specs and it works great.