Chevrolet Chevy Van Forum : “I am looking for info and a manual for a 1990 LMCchey van ”

If you take your van to a Chevy dealer, they can run the vin and tell you who did the conversion. After that they might be able to get you a manual your, with the name of the company you can look on the net. But as seeing that Conversion vans haven't been a hot ticket in many years, the company that did the conversion might not be in busness, That is a strong possiblity. Aside from the coversion, the van is a 1990 3/4 ton chev van, all mechanics and drivetrain parts are for a 90. Also once you have all the info on the builder you can try e-bay. Best of luck.