There's a death of a Janet Buchanan/DENNISTOUN at Cadder in 1856 aged 71, looking at that should give her parents' names.
That would tie in with the 1851 census I found on freecen:
Piece: SCT1851/626 Place: Cadder -Lanarkshire Enumeration District: 6
Civil Parish: Cadder Ecclesiastical Parish, Village or Island: -
Folio: 626 Page: 1 Schedule: 3
Address: East Muchcroft, Chryston
Surname First name(s) Rel Status Sex Age Occupation Where Born Remarks
BUCHANAN David Head M M 60 Farm 160 Acres (3 Men,3 Women) Stirlingshire - Campsie
BUCHANAN Janet Wife M F 59 Stirlingshire - Campsie
BUCHANAN William Son U M 30 Farmers Son Stirlingshire - Campsie
GRAY William Grnson - M 7 Scholar Stirlingshire - Campsie
GRAY Margaret Dau W F 35 Stirlingshire - Campsie
GRAY James Grnson - M 5 Scholar Stirlingshire - Denny
LEGGET James Servnt U M 32 Farm Servant Lanarkshire - Kilbride
MARTIN Alexr Servnt U M 24 Farm Servant Lanarkshire - Old Monkland
PARLAN James Servnt U M 16 Farm Servant Lanarkshire - Cadder
MCLAY Mary Servnt U F 28 Farm Servant Argyllshire - Islay
BROWN Christina Servnt U F 30 Farm Servant Argyllshire - Islay
REID Mary Servnt U F 25 Farm Servant Lanarkshire - Old Monkland
You didn't mention your Grandmother's name in the original post? so Margaret in the census above is yet another child.
SP show the family still in Cadder in 1861 [it's not on freecen yet] David and a William at least
BUCHANAN DAVID 1861 M 81 626/2 1/ 3 Cadder (Eastern District) Lanark
They were there in 1841 too:
Piece: SCT1841/626 Place: Cadder -Lanarkshire Enumeration District: 1
Civil Parish: Cadder Ecclesiastical Parish, Village or Island: Chryston
Folio: 4 Page: 21
Address: East Muckcroft
Surname First name(s) Sex Age Occupation Where Born Remarks
BUCHANAN David M 55 Farmer Outside Census County (1841)
BUCHANAN Janet F 55 Lanarkshire
BUCHANAN Willm M 15 Outside Census County (1841)
BUCHANAN Elinor F 15 Outside Census County (1841)
BUCHANAN Mary F 10 Lanarkshire
MCLEOD John M 20 Agricultural Labourer Outside Census County (1841)
GRAHAM Willm M 15 Agricultural Labourer Unknown
DAVIES Mary F 15 Female Servant Unknown
CAMERON Janet F 15 Female Servant Unknown
ages were rounded down in 1841 census.
What makes you think the 1866 death is your David? was it a son or daughter who signed it? the ages just seem a bit too far out, and there's no son called Alexander.
East Muckcroft farm is still there and still seems to be a farm - though the dwelling house looks new.
look at it here:
https://maps.nls.uk/geo/explore/#zoom=1 ... yers=5&b=3
slide the blue button to see modern map.