I have a 2003 Shimano 105 triple crankset. This uses the Octalink V1 BB.
I have the opportunity to acquire a NOS XTR Octalink V1 crankset cheap.
For some reason Shimano specifies that XTR cranks must be fitted to XTR octalink cranks only.
Is there any reason why XTR Octalink V1 cranks shouldn't be interchangeable with the 105 Octalink V1 cranks?
Here is the 105 BB-5500:
Here is the XTR BB-M952:
Apart from spindle length, what is the difference, and why would they not be interchangeable for either 105 or XTR cranksets?
They're compatible as far as the spline interface goes (I used to have Ultegra cranks with a XTR BB) but the chainline will be a few mm off and you may have chainstay interference. You can find the XTR BBs on ebay for ~$30, so it's not a big deal if you need to change the BB too.
Just be sure in case you go to other mountain bike octalink BBs that they are all V1 as V1 is not compatible with V2 (longer splines among other things). As for the two you mentioned, the xtr one is 3mm longer (as labeled in the pic, 109.5,112.5) and so your chainline will be too wide.
Road V1 triple takes a 118.5 bb
XTR MTB takes either 112.5 or 116
As Soil sampler noted, The XTR bb is shorter than the 105 triple crank specifies so you may have chainstay clearance problems. Also, is the XTR intended for a 73 mm bb shell instead of a 68 mm?