1990 Ford Bronco II
A/C Compressor and Components Kit

Once you find where your AC system is leaking from, you'll need to fix that leak and replace the drier filter at the same time (available for all Bronco II here: https://www.buyautoparts.com/buynow/60-30559)

After that, you'll need to flush the system very thoroughly. Parts designed to work with R12 refrigerant (like your original compressor) will still work with R134a as well, you'll just need to use PAG oil instead of mineral oil. You'll also need to get new line adapters for the high and low side AC ports so R134a hoses will connect; these are not vehicle-specific and would be in stock at any auto parts store (I bet even WalMart carries them) for around $10.

Every compressor we sell will have some oil inside to protect the part during shipping and the time it spends on our shelf, but you would need to drain it and add fresh oil prior to installation. If you can provide your vehicle information, we can look up the exact type and amount of oil and refrigerant required.