A 833 V code?

I pulled an 833 from a 75 dart yesterday that wasn't originally a 4 speed car and I'm trying to decode the numbers. I've looked all over and so far I've found it was build on the 5122 day (Aug 1975 I think) Most places online have guys asking about the C 99129 H casting on the gearbox but the one I have has reads C 99129 V and I can't find anything on that. It doesn't feel/look aluminum so I'm assuming it's not an OD? Pics below for reference. Thanks guys!

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