In or before 1984, could blood typing be successfully done on a four-year old sample of blood taken from the trunk of a car? The blood would have been soaked into either the trunk-lining fabric or in particle fiber board underneath the fabric.

I'm writing a piece of fiction that involves a murder and the use of blood typing to clear an innocent man.

This link may be helpful to you.
History of Forensic Science (http://www.umbc.edu/tele/canton/STUDENTPROJ/May.A/timeline.htm)

The dried blood sample could still be tested for blood t ype (as well as DNA now).