From MoparNorm:
Series 1 : (WDX B1, B2, and VERY early B3, first series box only);
53 3/4" wide at top rail, 20 5/8" tall, 54 1/8 total length.
Round top rail, small "Dodge" surrounded with raised oval, stamped logo.
Series 2 & 3 (B3, B4, C1, C3, C4, W300, W300M, WM300):
54 1/2" wide at top rail, 55 5/8" total length, 21" tall, square top rail.
"Dodge" stamped large the same as the Sweptline Era logo.