A labelled photo of Chevrolet A-D vs GMC ND frame front cross member is attached below (illustration compliments of Rob English).

Note: GMC 228/248/270/302 blocks/engines are longer than Chevrolet 216/235/261 blocks/engine (GMCers say this produces long-block-envy by Chevrolet stove-bolters).
Attachments
GMC_Chevy_FrontCrossmember.jpg (39.85 KB, 141 downloads)

Tim
1954Advance-Design.com
1954 3106 Carryall Suburban
1954 3104 5-window pickup w/Hydra-Matic
The 216 and early 235 engines are not "splash oilers" -- this is a splash oiler.