I have a Colt SP1 that I bought in 1979 that I want to install a Colt collapsible stock on. The stock on it now is an A1 type. Can someone please give me step by step instructions on removing the old stock and installing the new one. I bought a CAR stock wrench from Bushmaster for the job. Thanks!

Be sure you have some moly di-sulfide grease (it is called for on the threads).  Its a couple of bucks for a can of it at most auto-parts stores.

Next download the -23&P from old.ar15.com/books.  In there you will find complete instructions (with pictures) for removing the old stock and installing the CAR stock.

Tip:  Be sure to cover the lower with a (heavy) towel when removing the fixed stock's buffer tube.  It holds in the Buffer retaining pin and it will FLY if you don't cover the lower.

BTW questions like this are best posted in the Maintenance section.  If you searched there you will find it has already been answered and the links to the manuals are posted.

I put my stock inbetween the vertical rails on my deck and then ran a crow bar wrapped in a towl up through the mag well.  On quick, hard torqued twist and it came off easily from there!