Gona need a clutch soon.

Hey...my 1986 Gen 1 with a G63B is going to need a new clutch soon, it's slipping under heavy load...I'm looking to upgrade from OEM as I often carry about 500 lbs. of equipment in the back. I recall BradMph picked up a formula 1 from Exedy for I believe $95.00...I went to their website and they do not list that clutch as being available at this time only the OEM....does anyone have suggestions on where to buy and what brand, obviously I want a great price but more importantly....reliability. Thanks in advance...