There are a few points to bear in mind that account for quite a bit of the variation -
1. That 63,000 crowd was for the derby, there was probably at least 15,000 rags in the ground.
2. A much lower proportion of S/T holders, we only had about 10,000 then compared to 44,000 now so there was a much higher proportion of pay at the gate spectators.
3. For the vast majority of people it was a cash-based society, no plastic, if you didn't have the money on Saturday morning you weren't going to the match (unless you jibbed in!)
The last two home games you refer to were both night games - Thursday and the following Monday - plus we were the outsiders for the title at that point, we'd dropped 3 points in two away games and it looked as if we'd blown it. Leeds and the rags were the favourites at that point but both dropped key points around that weekend which left us in pole position although we still had to win two difficult away games to clinch it.