What type of gearbox do you have?
General Motors family tree
Powerglides - 2 speed orginally cast iron typically found in 57 chevy's. a weighty lump but very reliable. Air cooled bellhousing
Aluminium Powerglides - still 2 speed but lighter - sort after for drag racing for their shear strength
TH350 - all aluminium 3 speed - very dependable and stands abuse - sat behind millions of 350 motors. 4x4 versions. Fails with neglect and old age.
TH400 - more of a big brother to the TH350 - very strong but heavy and saps more hp to drive through it. Stands 500hp stock, 1000hp with upgrades. They just go on and on forever - fitted to mostly big block motors and Jaguar V12's Ferrari's and Rolls Royce so that says it all really
TH700R4 - first evolution overdrive - 0.70 in 4th gear. Has a lockup convertor for extra economy. Suffers from 3rd gear clutch failure in stock form.
TH700R4 - second evolution - larger input shaft - other internal changes - still suffers faults in stock form but better than the previous.
TH200-4R - medium duty overdrive from the 80's - excellent ratio spread - Can live behind a big block with mods - multicase bellhousing
4L60 - a 700R4 renamed! - More internal changes - best box of the overdrive bunch - still can fail unless parts upgraded - can be ok for 500Hp
4L60E - electronic controled version of above. ECU controlled gear changes. No good for old chevy engines without ECU's. Needs an aftermarket transmission control unit to function which can be £600.
4L80E - bigger brother of 4L60E and electronic equivelent of TH400. Strong with overdrive. Bentley worthy big beast. Again dumb without an ECU.
FX and MX -ford-o-matic / cruise-o-matic - yep! err?*! Early auto's best left in the scrap yard really.
FMX - evolution of above 2 types - Guts of an MX in a FX case. Alloy bell with cast iron case. Heavy.
C4 - 3spd - All aluminium - seperate bell housings - 2 types, case fill (smaller) pan fill (larger) - fitted to everything you can think of due to the multiple bellhousings. Strong and reliable, only fail with age. Caution when interchanging parts like bell/ torque/flexplates! Some stuff just doesnt go!!
C5 - oilway modified slight variation of C4 - valve body mods - otherwise the same animal.
C6 - Big bruv to C4 - All Aluminium - Heavy duty like a TH400 - uses more HP to drive but stands abuse - best behind a 390 / 428 in a full body.
AOD - first 4speed - All Aluminium - weighty box - meaty parts - clever dual input shaft does not rely on lock up converter but does 'lock up'. Complex!
AODE - Electronic version of above - needs ECU to function like a 4L60E.
Powerflite - 2spd - Cast iron - no park setting so dont forget the handbrake!!
Torqueflite - A904 - light duty 3spd - All Aluminium - reliable - mostly used on 6 pots
Torqueflite - A727 - Heavy duty 3spd - All Aluminium - this is the common box found in a ton of Mopar cars like the Dodge Charger. Strong and dependable behind a 440. Also used in Jensen Interceptors.
Torqueflite - A518 - overdrive version of above 727.
Torqueflite - A618 - Electronic overdrive version of 727
Although really part of the GM tree these deserve an entry of their own
Dynaflow - Cast iron 2spd - damn strange - 220lbs!! weird dismantlable torque converter - short but wide - strickly in your 50's Buicks
Hydra-matic - 4spd - ditto weighty lump above - even heavier. 50 /60s Caddy's Old's. Not for the fient hearted to take apart.
Jetaway - 4spd - 50/60's Cadillacs - all these boxes are becoming hard to find parts for and those parts price themselves accordingly!