It was definately very crowded, I can vouch for that! My personal feeling was that the Bournmouth match earlier that season was even more packed - but that is very subjective; it may have depended on exactly where you were standing.Rochdale '72 was an epic night. 35,000 in the ground and 10,000 locked out? That is how it was reported anyway.
Twenty five thousand average home crowd for that season!