Which Bumper is correct?

[MY1978]

I am replacing the current step bumper on my '78 fleetside with a period correct bumper that my truck originally came with.  It has been called a "sport" bumper, like a blazer had on it.  I am so confused.  When I look up rear bumpers from suppliers, I find two different styles of rear bumpers.  It has been so long since I saw the original bumper that I am not sure which is correct.  I have attached pics of the two types.  If memory serves me right, bumper "A" is the correct style, yet many sites sell bumper "B" as a '78 rear bumper.  Bumper "B" to me looks like something that goes on a step-side truck.  Please help!!!!

[Shifty]

Almost sure it is style "A". 

[MY1978]

Thank you.  I have contacted whom I purchased from and they see the problem.  Also, the box it was shipped in says "Chevy P/U Bumper rear fleetside 67-72 painted".   After a lengthy conversation via chat and assurance that this was the correct bumper (even though t  She picture was different), this was my second clue that there was a problem.  Told them they have a serious problem in their warehouse that needs some fixing.  They are forwarding to QC to look into.  Anyway, they are sending back at their cost.

[VileZambonie]

A = 73-80

[philo_beddoe]

I have a 77 and I bought A from the site store, good quality bumper. It may have come from the Chevy factory in Detroit.  Lol…