David -
The easiest thing to do is take your model number to SearsPartsDirect.com and enter it there. You'll get the machine's original parts list pages which you can browse online and print if you want. Selecting a specific part will yield the original part number if the item is NLA (so you can search for it elsewhere), find out if the part is current, and what the new number is if any. If Sears has it in stock, they'll quote you a price.
There were four variations of the 1972 Lady K (one was from changing the tub ring from metal to plastic). Without having your model number, it's tough to say for certain on a particular part, but I know the belt covers every skinny belt model there was. I know they are plentiful, part number 96388. I think they are cheaper elsewhere than at Sears. The hose is a different story. It's part number is 357006 now, at least as it applies to my '72 Lady. This hose is NOT plentiful and I suggest your grab one wherever you can find it. The part number given is for large tub models, which is simply longer than the standard cap tubs used in '72 Lady Ks. This is a Whirlpool authorized sub. which was done when the '72's hose went NLA.
Please verify that your specific model also requires this hose. When removing the old hose from the triple dispenser, be VERY careful not to crach the dispenser or break the hose mounting area. These dispensers are very expensive when they can be found.
Gordon