actually from what i have found was that they finished sometime in May of 74
i have found 2 while searching the net that the owners claimed were made in
early May/74 and both were B5 blue, one guy on this site and thread
http://www.cuda-challenger.com/cc/in...?topic=72872.0
claims he had the second to last one made so you may want to sign on there
and see if he still has the vin number and or remembers the date on the fender tag.

unfortunately i cant remember the other site where i seen someone had posted their
may/74 build.

with your april 29th build date i assume you have your fender tag and have decoded it.
Body Type: J = Challenger
Price Class: H = High
Body Type: 23 = 2 Door Hardtop
Engine: G = 318 150HP(net) or 170HP(net) 1-2BBL 8 CYL
Year: 4 = 1974
Sequence Number: 397511 = 297511th Vehical Built

by the way what color is yours?