71 Dodge Dart Swinger in England

ok i have the diff out now and struggling to get the sliding yoke out, so that's tonight's job. its either jammed in the transmission or the prop is too long as there is no movement to slide the prop forwards. I had to dismantle the rear UJ to get the prop clear of the diff. So still not getting closer to the the engine vibrations. But need to sort all these things out before i can go for a run in it. With the prop off the exhausts off and the car nice and high on stands i might as well take the trans out and change the flex plate. Oh did I mentions the trans sump is so distorted and over tightened and covered in red sealant that it leaks from every seam. So there's another job.
Does this date stamp on the diff say 1975?
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looks like the axle has been shortened one side form the donor car, the splines on the drivers side look new and looks to have the DART written in white paint on the halfshaft, again suggesting very low miles since fitted.
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All the brake drum internals look new
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Ive counted the crown wheel and pinion teeth 35 and 10 , so 3.5 ratio, anybody recognise these markings on the crown wheel?
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