Following this with great interest - I'm so glad you have found each other!
JKC - if the record is from the 1841 Carluke census, then Crawford Street will definitely be in Carluke not Motherwell. The parish of Carluke in 1841:
"Town of Carluke divided as follows viz. on the East by Carluke Burn, on the South by an ideal line drawn about 200 yards South of and running parallel to Caluke Burn on the West by the parks of Kirkton and on the North partly by a road leading from the parish church of Carluke to the Windmill Quarry and partly by an ideal line drawn East from the Windmill Quarry to Carluke Burn."
If you go to Old Maps, you can find Crawforddyke street on the 1864 map, which may well be it. Go to:
http://www.old-maps.co.uk/indexmappage2.aspxand put Carluke in the search box at the top, then choose it from the drop-down address matches.
You will see a map appear and should see a "main" road sticking out to the East of the town. Pan and zoom in to that and you will see its name.
By the way, for an in-depth study of Carluke around the time your ancestors were there, go to the Statistical Accounts. These were written by the ministers of the time about their parishes and vary considerably in their coverage. The Carluke one is rather besotted with geology and alluvial deposits (!), but persevere and you get some very interesting facts, like marriage and burial customs for example. It was written in 1839 so would be accurate for your timescale.
Go here:
http://edina.ac.uk//stat-acc-scot/Forget the logins and look for the non-subscribers link at the bottom "Browse scanned pages".
Then enter Carluke in the top search box.
There were 2 statistical accounts performed, one in the 1790s and one in the 1830s-40s, which is the one you would want. Click the link and start reading!
I have found the statistical accounts invaluable for giving a snapshot of what life was like in Scottish parishes of the time.
Jo