Model U- Updated 10/04/2022

Registry Insight- Model U

Introduced in 1929 the Model U stayed in production until late 1952 with early machines powered by a Continental 283 cubic inch engine before changing in 1932 to the 300 Cubic Inch Waukesha engine and finally in 1936 to the Allis Chalmers UM 318 cubic inch engine. The Model U was sold as the United by the United Tractor company. The Model U was the first tractor ever fitted with rubber tyres (which were aircraft tyres on the rear) which became an option in 1932. Steel wheels were still available but Rubber Tyres were the way forward particularly after legendary race car driver Ab Jenkins clocked 68mph on a Firestone rubber tyre equipped Model U at Bonneville in 1935. The Model U was rated at 24-drawbar hp and 34-belt hp
Shown below is a 1936 built variant which is crank start with no lights or PTO.

 Shown below is a later Model U equipped with starter and lights

Above is U1454 which is a United Badged Continental Powered version

Model U serial numbers are as follows, note that tractor numbers U1-U7404 were equipped with Continental engines before a change at U7405 to the UMA prefixed Allis Chalmers engine. The serial number can be found on rear of differential housing for model U, IU and UC variants. Engine serial number centre of left side of block for S10 Continental Engines; right side of block below oil filter on UM engines.

1929-     U1-U1974

1930-     U1975- U6553
1931-     U6554-U7261
1932-     U7262-U7404
1932-     U7405-U7418
1933-     U7419-U7684
1934-     U7685-U8062
1935-     U8063-U9470
1936-     U9471- ?
1937-     ?- U14854
1938-     U14855-U15546
1939-     U15587-U16077
1940-     U16078-U16721
1941-     U16722-U17136
1942-     U17137-U17469
1943-     U17470-U17801
1944-     U17802-U17819
1945-     U18022-U18324
1946-     U18325-U20773
1947-     U20774-U21021
1948-     U21022-U22127
1949-     U22128-U23028
1950-     U23029-?
1951-     U22548-?
1951-     U22561-U22823
1951-     U20513-U20585
1952-     U20586-U20748
1952-     U22824-U23056

Discrepancies are shown in 1951 and 1952 serial numbers and production did occur in 1953 but tractors were not available for order in Allis Chalmers dealerships, these were direct orders with the factory.
Below is a list of the Model U variants currently in our register now at 99 units. If yours is not listed please get in contact with us so it can be added. A lot of the tractors on this register were compiled by the late Owen Triggell, if you own one of the tractors listed please let us know so details can be kept up to date. A copy of the Register Form can be found here.

Updated 10/04/2022

MODEL	YEAR	SERIAL NO	ENGINE NO	DEALER ID	STATE	CONDITION
United	1929	U01454	3S101551		VIC	unrestored
U	1929	U01491			NSW
United	1929	U01941			NSW
U	1930	U06147
U	1930	U06155
U	1930	U06205
U	1933	U07559			VIC	Restored
U	1935	U09126
IU	1935	U10046
U	1935	U10069	UMA13725		QLD
U	1936	U10320
U	1936	U11276
U	1936	U12072	UMA6480K		VIC
U	1936	U12121		Lanes U39	VIC	Restored
U	1936	U12523			VIC
U	1936	U12526
U	1936	U12528
U	1936	U12566
U	1936	U12579				WRECK
U	1936	U12586	UMA88890K	Lanes U58	VIC	Restored
U	1936	U12995
U	1936	U13041				WRECK
U	1936	U13059
U	1936	U13137
U	1936	U13138				WRECK
U	1936	U13141
U	1936	U13292
U	1936	U13312
U	1936	U13378
U	1937	U13418				WRECK
U	1937	U13477				restored
U	1936	U13519				WRECK
U	1937	U13548			VIC	unrestored
U	1937	U13564			VIC
U	1936	U13574				WRECK
U	1937	U13594
U	1937	U13636
U	1936	U14153
U	1937	U14154
U	1937	U14206			VIC
U	1936	U14512
U	1936	U14651	71137S		SA	original
U	1936	U14678
U	1937	U14709
U	1937	U14719				WRECK
U	1937	U14736			NSW	Restored
U	1937	U14754			VIC
U	1937	U14820
U	1938	U15026				WRECK
U	1938	U15084
U	1938	U15249	2153S		SA	parts only
U	1938	U15264				WRECK
U	1938	U15407			VIC	unrestored
U	1938	U15416			VIC	unrestored
U	1939	U16070
U	1943	U17653
U	1943	U17783
U	1946	U18487
U	1946	U18528
U	1948	U21031
U	1948	U21053
U	1948	U21066			QLD	Restored
U	1948	U21482
U	1948	U21602
U	1949	U21775			QLD	Restored
U	1948	U21845
U	1948	U21883	UMA36637K		QLD	Restored
U	1948	U22050	2006229		VIC	Restored
U	1948	U22067
U	1948	U22076				WRECK
U	1949	U22178			VIC	unrestored
U	1949	U22179
U	1949	U22266
U	1949	U22270			SA
U	1949	U22301
U	1949	U22525			VIC	Restored
U	1949	U22538			VIC	Restored
U	1949	U22539
U	1949	U22543
U	1951	U22569			WA
U	1949	U22576
U	1949	U22638
U	1949	U22701				WRECK
U	1949	U22767
U	1949	U22839
U	1949	U22841
U	1949	U22842
U	1949	U22885				WRECK
U	1952	U22888			VIC
U	1949	U22897
U	1949	U22901			QLD
U	1949	U22905	UMA39211K		NSW	unrestored
U	1949	U22932				WRECK
U	1949	U22934
U	1949	U22944			QLD	project
U	1949	U22959
U	1949	U22986				WRECK
U	1952	U22989			VIC
U		U22990	UMA39050K		VIC	unrestored
U	1949	U23005
U		U24573	UMA14763K		VIC	Wreck
U	?	U76375?
U					NSW	Restored
U					VIC	Restored
U	1938				WA	Restored
U	1950?				VIC
U	1948?				NSW
U	1949				NSW
U	1948				NSW	unrestored
U					NSW	unrestored
U					QLD
U					SA	Restored
U					VIC	unrestored
U					SA	unrestored
U					NSW	project
U					NSW	wreck
U					NSW	unrestored