John, it sounds like you have something that has broken inside the
transmission.  You could remove the two bolts that hold the rear part of
the linkage up and drop the rear part of the linkage down and out of the
way.  Now try to move the shifter lever that is on the side of the
transmission and has the plastic ball on the end.  If it doesn't want to
move then something inside the trans has broken.  If the shifter arm
will move then you have a linkage problem.

Let me know if I can help you further.
Ken Wilford
John 3:16
www.vanagain.com

John Rodgers wrote:
> Subject line says it all.
>
> I had no warnings of any pending trouble with this transmission. It was
> rebuilt back in 1998, never had a llick of trouble from it since the
> rebuild. Now this mornings, as I was backing out to drive 100 miles to
> do a two day art show - stuck in reverse. I know about a lot of other
> stuff on the van, but never working with the shifter, linkage and tranny.
>
> Any ideas?
>
> Thanks.
>
> John Rodgers
> 88 GL Driver
>