i have a 94 g-20 conversion van that has recently started marking its spot in my garage,i crawled underneath and saw that where the tranny goes into the driveline is covered with oil(?)so i would suspect that i need a rear seal.....can any one tell me how dificult it would be for a broke amatuer to afford and fix

 

Motor oil? Rear main seal is leaking, or front seal and blowing back.
Not a diy project.
You could switch to high mileage oil. The higher zinc swells worn seals. Might do for a while.