I’ve been working on a 1951 olds 88 that I recently purchased. Recently got it to the point to take it on a test drive. Car shifts fine into all selections, n, dr, lo, r. But during the drive, it was unable to shift from 1st into 2nd. The car bogs down and will shut off. Restart it, put it in dr, and the same thing happens once I reach speed. Tried in LO and same issue. Fluid appeared to be low, added fluid. Seems to be more responsive when shifting into gears, but still the 1st to 2nd issue. Any ideas on what I should look to do next? Thanks for your ideas and help in advance!