I assume that they ran out of 4 letter combinations or did UPS buy out the remains of REA?
One site listing the various REA root reporting marks offered the following:
REA RAILWAY EXPRESS AGENCY, INC.
REAL (REAZ) TRANSAMERICA LEASING, INC.
REAU (REAZ) TRANSAMERICA LEASING, INC.
REAZ *GRAND TRUNK WESTERN RAILROAD CO. (REPORTING MARK ELIMINATED MAY 1983)
REAZ +DELAWARE & HUDSON RAILWAY CO. [DENVER & RIO GRANDE WESTERN RR CO.; GRAND TRUNK WESTERN RAILROAD CO.; MAINE CENTRAL RAILROAD CO] / TRANSAMERICA TRANSPORTATION SERVICES (TRANSAMERICA LEASING, INC.)
Two others list them thusly:
REAU Transamerica Leasing Incorporated
REAZ TIP Intermodal Services
I’m not sure about the other reporting marks but REAU would be applied to containers and REAZ would be applied to trailers.
Transamerica was founded by by A. P. Giannini who founded Bank of America…Nothing yet I oculd find onthe reporting marks…though I did find that UPS sued REA in 1975
REAZ never was the reporting marks for the Railroad Express Agency. No connection what so em-ever. The other REAU and etc., is no relation.
Here’s what you need to see: http://www.krunk.org/~joeshaw/pics/pvt-tofc/reaz/
Oogle Google has other answers for you as well. A quick search revealeth much.