Not only can I also confirm that they were OS height markers (didn't older OS maps used to print the height of each marker at its location?), I'm also very familiar with the one in your photos, having spent most of my life in that particular corner of Cambuslang!
This is actually a really good example to demonstrate how they worked - heights being calculated by relating the pillars to each other. From this particular one, you can see two others, although one is now obscured by new housing. The first one is up on top of nearby Dechmont Hill, to the south, easily seen next to the flagpole at the summit. The other is lower, on Newton Station Road to the west, next to the new Hallside Primary School.
Believe it or not, the pursuit of these trig points is something of a hobby for some people, and the one at Hallside Primary is particularly sought after due to it being fenced off and in the grounds of a school!
On a slightly different note, this area has a couple of sites I've always thought well suited for the Hidden Glasgow treatment. One is the army rifle ranges at the foot of Dechmont Hill, still in use as a live ammo firing range, but if you venture that way when the flags are down, there are rows and rows of old, disused target trenches, some of which are now hidden in woods!
Also nearby, just over the Rotten Calder River, next to Blantyrefarm Rd (just where the B758 writing is at the top right of the Multimap link in the earlier posting) is another old WWII AA gun emplacement site which is relatively well preserved, despite some of the structures being partially buried now. Keep meaning to venture out and take some pics for submission, if anyone is interested!