I have a preban Colt Sporter M4 with double shield handguards.  The buttstock is telescopic and is colt mfg.  That means I have a top slot on the buttstock and a side swivel (and bottom swivel) near the front sight.  Call this my Colt.

I have a preban bushmaster lower, colt M4 double shield hanguards witha six position (I thinkRRA) with a bottom swivel on the six position buttstock.  I also have side swivel (and bottom swivel) near the front sight.  Call this my bushy.

Which sling for these and does it appear that they require different slings due to the config of the buttstock?

I was thinking the Rock River CMP as a cheap spare and maybe a CQB solutions #135 or 136.  Please assist with the decision and where is best place to buy.  Thanks in advance folks.

The #136 would work with either of the two stocks.  It mounts using the sling slot at the top of the stock.  The #135 is for standard handguards, not the fatter m4.  If you are going to use the side swivels on the front of your rifles I would recommend the #137.  It uses the swivels instead of mounting to the handguards.

Just to make things more confusing you could also use the #200 sling which includes adapters for the M4/A2/M203 setups.  This is kinda nice to have if you ever switch furniture, or move the sling to a different AR.

I stock most of the CQB slings and try to offer them at the best price.  $36.95 plus $5 shipping USPS priority with delivery confirmation.  The #200 are $38.95.  Usually ship the same day I receive payment.  Money order/paypal with no fee.

Let me know if you have any questions.

Thanks
Adam