The following changes occurred during the production run of the TE20:

(This can be one way to determine when your tractor was produced. If you have the engine serial number or date codes from  the transmission casting, check
here for more information.)

Serial  
Number    Change

1001          Lucas starter model M418G, service number 25505B with terminal on yoke employed.
15883       Lucas starter model M418G, service number 25519A with terminal on end bracket employed.
30661       Generator changed from model C45X-22415A to C45X-22420B
43074       Lucas starter model M418G, service number 25519D with rubber type drive employed.
56339       Oil filter changed from vertical to inclined type.
71001       Gas tank mounting changed from bolts and lock washers to bolts plus double rubber pads at
                   the battery box and a single rubber pad at the gas tank.
74540       Gas 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.
                   Shield added over safetty valve on hydraulic pump.
172598     Engine bore increased from 80 to 85 mm (hp up 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 changed from kidney cam to floating cam.
200928     Brakes changed to kidney cam.
201144     Brakes changed to floating cam.
201147     Brakes changed to kidney cam.
201157     Brakes changed to floating cam.
201618     Brakes changed to kidney cam.
201622     Brakes changed to floating cam.
201625     Brakes changed to kidney cam.
204666     Brakes changed 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 shutoff 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 zerk 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.