This information is for the Ferguson TEF20 tractors, and identifies any changes that have occured during the production of the tractors. This list can help identify the serial number of your tractor if the identification plate is missing. This information below is an extract from the Wallaces website.  Unfortunately, the Wallaces Ferguson website does not seem to exist any longer.  This is a shame, as they had a nice chart which was a cross-reference between the TE20 engine number and serial numbers.  If anyone knows of a similar resource then please let Vintage Tractor Engineer know, as this would be good information to have available.


1001 Lucas starter model M418G, service number 25505B with terminal on yoke used.
15883 Lucas starter model M418G, service number 25519A with terminal on end bracket used.
30661 Generator changed from model C45X-22415A to C45X-22420B
43074 Lucas starter model M418G, service number 25519D with rubber drive used.
56339 Oil filter changed from vertical to inclined type.
71001 Fuel tank mounting changed from bolts and lock washers to bolts and double rubber pads at
the battery box and a single rubber pad at the gas tank.
74540 Fuel tank mounting now has double rubber pads at both front and back.
96932 Oil catchment rings riveted to brake drums to protect brake shoes.
113158 Rubber cap added to plug on top of hydraulic pump valve chamber.
119107 Oil retaining shim located between base of bearing cup and retainer in rear hub.
134001 Oscillating control valve on hydraulic pump introduced to minimise control valve sticking.
Cover added over safety valve on hydraulic pump.
172598 Engine bore increased from 80 to 85 mm (hp increase from 23.9 to 28.4)
Water pump mounted on head instead of block.
200001 Electrical system changed from 6 volt to 12 volt.
Hole in block for starter motor increased from 2 7/8″ to 3 1/2″.
Air intake now via screen on dashboard.
Two additional oil pressure take-off points with socket type screws added in hydraulic lift cover.
Brakes altered from kidney cam to floating cam.
200928 Brakes altered to kidney cam.
201144 Brakes altered to floating cam.
201147 Brakes altered to kidney cam.
201157 Brakes altered to floating cam.
201618 Brakes altered to kidney cam.
201622 Brakes altered to floating cam.
201625 Brakes altered to kidney cam.
204666 Brakes altered to floating cam once and for all.
225160 Independent brake linkage bush lubricators introduced.
268153 Hydraulic lift cover strengthened.
Hydraulic ram cylinder strengthened.
286543 O-rings used instead of gaskets to seal valve chambers to hydraulic pump.
294147 Fuel shut-off valve changed from round to rectangular.
325001 Crown wheel diameter increased from 12.66″ to 13.15″ (length of teeth increased)
Length of teeth on pinion gear increased to match crown gear.
Diameter of holes in centre housing (differential case) increased to accommodate larger
crown wheel.
Number of studs holding axle housing increased from 11 to 15.
Axle trumpet diameters increased to mate with centre housing.
Hub bearings became grease lubricated; grease nipple fitted at outer end of axle trumpet.
Inner oil seal added inside the axle housing.
Top diameter of axle splines increased.
Number of teeth on differential gears reduced from 20 to 16.
325572 (Petrol tractors only) Plate added to side of fuel tank to prevent petrol from spilling on
ignition wires during refueling.
330044 Hydraulic safety valve moved from pump to left hand port of lift cover.
Thread size in right hand port of lift cover changed from 3/8″ x 18 NPTF to 1/2″ BSP.
Socket screw in right hand lift cover port changed to flanged type hexagon nut with washer.
Lift cover strengthened around ram cylinder attachment points.
Oil port to ram cylinder in lift cover undercut to receive O-ring, instead of using gaskets.
381660 Voltage regulator changed from bolt-mounted model RF97 to rubber-mounted model R107
407102 Key rod replaced by metal drive strip at end of control valve in hydraulic pump.
429519 Poppet type safety valve in hydraulic lift cover replaced by steel ball type.

(A very copmrehensive list from the Wallace website, please visit the site for more detailed information.)