Marketing of the "Unit Plan" lathes, as distinct from the company's Utility Models, was aimed at the impecunious owner could afford to start with a basic but functional lathe in non-backgeared, plain-turning form and then add, as funds became available, all the items necessary - motor countershaft unit, backgear and screwcutting attachment - to turn it into a fully-specified machine.
Based at first on the 9-inch compound V-belt drive lathes, eventually the range was offered with the swing increased to 10 inches and (if chosen) a countershaft resembling that fitted to the first of the later 10-inch screwcutting lathes. The versions available started with a basic machine, the $39.50 10A, with a plain slide rest, no rack feed along the bed and no backgear or countershaft unit (this lathe was also the basis for a new range of wood-turning lathes that were introduced by Sears, Roebuck in 1935 and sold under their Craftsman label). The $49.25 Model 10B added a complete 8-speed countershaft unit but retained the non-backgeared spindle and plain compound-slide rest while the $54.75 10C was, in effect the fully specified ($87.50) model less the screwcutting equipment. All types were available with between-centres' capacities of 18", 24", 30" and 36" and a choice of plain (babbit) or, at an additional cost of $18.50, Timken tapered roller bearings in the headstock
The countershaft assembly was $12.50; a rack-and-pinion drive for the carriage from $13 to $13.75 (depending on bed length);  the 10C-type compound slide $9.85; a backgear assembly $8.35 and  the screwcutting attachment with changewheel set, reversing gearbox and bracket from $12.75 for the shortest-bed version to $15.95 for the longest.
With the introduction in 1936 of the new 10-inch Atlas lathes the "Unit Plan" machines were revised to incorporated many of the same improvements but, in line with the poor trading condition of that era, at a lower price. The lathes continued the Company's tradition of offering the less-well-off owner a basic but functional lathe in non-backgeared, plain-turning form that could be added to - a motor-countershaft unit, backgear and screwcutting attachment - as funds became available. As before, the basic machine was the 10A ($35.50) with a plain slide-rest (no rack feed along the bed) and no backgear or countershaft unit  The $45.25 Model 10B added a complete 8-speed countershaft unit but retained the non-backgeared spindle and plain compound-slide rest while the $49.75 10C was, in effect the fully specified ($87.50) Model 10D less its screwcutting equipment. All versions were available with between-centres' capacities of 18", 24", 30" and 36". Accessory prices remained unchanged, with the countershaft assembly at $12.50; a rack-and-pinion drive for the carriage from $13 to $13.75 (depending upon the length of the bed);  the 10C-type compound slide $9.85; a backgear assembly $8.35 and  the screwcutting attachment with changewheel set, reversing gearbox and bracket from $12.75 for the shortest-bed version to $15.95 for the longest.
By 1938 the "Unit Plan" lathes had disappeared from the lists and the only cheaper option available to the hard-up enthusiast was the final 36-inch capacity version of the original 9-inch all V-belt drive lathe - a model that was to be  dropped during 1939..

The basic machine in the "Unit Plan" range was the $39.50 Model 10A with a plain compound slide that featured a long-travel top slide, no rack feed along the bed and no backgear or countershaft unit.
This lathe was also the basis for a new range of wood-turning lathes that were introduced by Sears, Roebuck in 1935 and sold under their Craftsman label.

A payment of $54.75 secured the 10C that was, in effect the fully specified ($82.50) model but without its screwcutting equipment. Because this lathe had a rack-and-pinion carriage feed the compound slide (with its shorter-travel top slide) was from the screwcutting model.

The basic 1936/7 Atlas 10-inch "Unit Plan" Model 10A with plain slide rest and no backgear or countershaft-drive system.

1936/7 Atlas 10-inch "Unit Plan" Model 10C with a simple rack-feed carriage, a full countershaft-drive unit - but no screwcutting facilities.

Advertised unashamedly as the "Utility" model bench lathe, this rare 9" x 18" machine had a production run that lasted from 1934 until 1938. Although it  retained the screwcutting facility of the better-specified lathes, it had only 6 spindle speeds (202, 330, 530, 610, 1015 and 1625 rpm) obtained by the use of a 3-step pulley on the headstock and a double-step pulley on the motor to countershaft drive.
On the original "918" version not only was no backgear, but also no top slide, that being replaced by a toolpost formed as an integral part of the cross slide - a poor marketing decision that prevented the owner from ordering one from the accessories list.
Two other 918 models were available: the 918A, which came with a complete set of changewheels to cut threads from 4 to 96 t.p.i. and the 918B, which had, in addition, a graduated, swivelling compound slide rest..