1968 Dash Harness Question

[damnyankee36]

I discovered something odd on a 68. The fuse box has the main harness coming out of the left side. The American Autowire harness I bought, (#33915), has the harness coming out the top.

I thought I got the wrong one but it specifically says it's for a 67-68. What's weird is that AAW's 69-72 harness, (#30100), shows the harness coming out the side like the 68 I have. The fuse layout is the same but it's upside down.

Is it possible that I have a late build and they started using the 69 harnesses in 68? I suppose it's possible that the harness was changed out but I have my doubts. It looks very aged and original.

How can I tell what the build date is without a build sheet?

EDIT:

Been doing some research. The rear end has E118 casting date. I'm gonna guess that's May 11, 1968. Fairly late in the model year.
The transmission is a TH400 with these #'s on the tag: 546 at the top right. At the bottom: CT-68-77380. The 546 is the Julian date, which didn't make sense until I saw a reference stating the date codes started January the year before. So that would make a Julian date of 181 or June 29, 1968. Close to the rear end cast date.