Notes: Powerglides for the 253 and 308 were 6 cylinder units with a bolt on bellhousing. Powerglides on the 307 and 350 had an integral bellhousing.
HQ-WB
Rev
1st
2nd
3rd
4th
M15 Aussie 3spd (6cyl, HQ 253)
-3.59:1
3.07:1
1.68:1
1.00:1
M20 Aussie 4spd Std. ratio (L6)
-3.05:1
3.05:1
2.19:1
1.51:1
1.00:1
M21 Aussie 4spd Close ratio (V8) (High Perf.)
-2.54:1
2.54:1
1.83:1
1.38:1
1.00:1
M22 Aussie 4spd Wide ratio (L6) One Tonner
-3.72:1
3.74:1
2.68:1
1.68:1
1.00:1
MC7 Muncie
-2.59:1
2.52:1
1.88:1
1.46:1
1.00:1
M40 TriMatic (L6, 253, 308)
-1.85:1
2.31:1
1.46:1
1.00:1
M41 TH400 (308, 350)
-2.08:1
2.48:1
1.48:1
1.00:1
Trimatic ID Plate Codes:
HG Holden
HH
All 6 Cylinder execpt high performance
HJ
All 6 Cylinder high performance
HQ Holden
HN
173 (2.85L) 6 Cyl
HT
202 (3.3L) 6 Cyl
HO
253 (4.2L) V8
HP
308 (5.0L) V8
HJ Holden
HN
173 (2.85L) 6 Cyl
HT
202 (3.3L) 6 Cyl
HO
253 (4.2L) V8
Notes: From HJ onwards, the Turbo 400 replaced the Trimatics behind 308 V8's
HX/HZ Holden
KJ
202 (3.3L) 6 Cyl
KK
253 (4.2L) V8 with all diff ratios except 2.6:1
KX
253 (4.2L) V8 with diff ratio of 2.6:1
WB Holden
FU
202 (3.3L) 6 Cyl with all diff ratios except 4.44:1
FV
202 (3.3L) 6 Cyl with diff ratio of 4.44:1
FX
253 (4.2L) V8
FW
202 (3.3) 6 Cyl with 4.44 diff and T-Bar Floor Shift
GM Transmission Identification:
Tri-Matic
Trimatic ID Plate. The very large HT letters define this as being from an LH, HQ or HJ Holden. The F Calibration relates to the Band tightening requirement.
GM 3 and 4 Speed Automatic
All GM transmissions are fitted with the standard small-/big-block Chevy bellhousing bolt pattern. They include the TH350, the TH400, the TH200-4R and the TH700-R4. A quick way to differentiate the 350s and 400s from the later boxes is by the vacuum modulator. Note: Sometimes it's easiest to identify an automatic by its pan shape. Here, from left to right are the pans for the TH700-R4, the TH200-4R, the TH400 and the TH350.
GM Transmission Dimensions:
Transmission
Length
Rear Transmission Mount Position
Powerglide
27
19.5
T350
27
19.5
T400
28
26.25
TH200-4R
27
26
TH700-R4
30
21.25
Note: All dimensions are in millimetres (inches). Length is measured from the bellhousing mounting flange to the end of the extension housing. The transmission mount position is also expressed from the bellhousing flange rearward to the centerline of the mount. The TH400 length and mount dimensions are for the "shorty" tail-housing model. There may be other transmission models in which these lengths may vary, but these are the popular models.
