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

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