The Atlantic Coast Line did have two bay covered hoppers with the triangular cutouts between the hoppers in the sidesheets. Morning Sun's "Atlantic Coast Line Color Guide to Freight and Passenger Equipment" shows three different classes of 1958 cu.ft. hoppers with the aforementioned cutouts and square hatches, in the following number series:
Class L-5: Nos. 86100-88099 Built by Pullman-Standard and, ACF
Class L-9: Nos. 88100-88399 Built by American Car & Foundry
Class L-4a Nos. 116000-116567 Originally built by ACF, in 1950-51. Rebuilt in 1966 by Chicago Freight Car Company with circular instead of square hatches.
A lot of ACL covered hoppers had sheet metal panels attached to the ribs to carry the reporting marks and weight data. You didn't mention the scale you model in but in HO, Intermountain-Railway offered an ACL car, which is probably out of stock which can be seen at: www.intermountain-railway.com
They currently have the best plastic models of the 1958 on the market (free standing vs. molded on, ladders and grabs), available in other roadnames. Decals for ACL LO's (covered hoppers) are available in multiple scales from K4 decals. They can be found at www.greatdecals.com. Click on "Suppliers" and scroll down. Good luck!
Bowser makes some:
https://www.bowser-trains.com/history/70tcoveredhistory.html
Also old Eastern Car Works kits if you are a masochist.
I have seen HO scale two bay hoppers with the center cutout. I believe they were resin casting cars. I don't recall the manufacturer. I do recall an article somewhere where the modeler modified and cut the center off of Atlas two bay covered hoppers and swapped the covers too.
Good luck.
Pete.
I'm looking to create a small fleet of ACL 2-bay covered hoppers, circa late-50's. The only photos of prototype cars I can find on line have triangular shaped cut outs on their sides. Photos of model cars show a more common car without the cutouts. Knowing that model manufacturers often create "foobies," did ACL have cars without the cut outs? If so, can someone supply a car number or range?