If this van has the 722.6 transmission . . . it does NOT have a dipstick, but it has a dipstick tube
The tube will have a black cap on it . . . this is NOT the dipstick
To check the level, you need a special tool, which you can find online, probably on ebay
There are many compatible fluids. Believe it or not, the factory fluid is not outrageously expensive, not in my opinion