A standard GM replacement...
A standard GM replacement (this one from Taiwan) shows three mounting holes. Depending on the year of the vehicle, two outer threaded holes secure the transmission tailshaft to the crossmember. Later-model tailshafts use only the center hole.
The bellhousing is connected...
The bellhousing is connected to the back of the block via six fasteners (sometimes five, depending on transmission type) with 3/8 x 16 coarse x 1 1/2 standard-thread bolts.
Small silver bolts secure...
Small silver bolts secure the shift detent cable and speedometer bracket on the transmission tailshaft.
The vital link: The top driveshaft is an aluminum unit used for Powerglide, Turbo 350, 700R4, and 2004R with a 27-spline yoke. The second unit, also with a 27-spline yoke, is for 4L60E and 4L65E. The bottom prop shaft is a Turbo 400 or 4L80E type with a 32-spline output shaft. In many cases, the transmission you're swapping in for a Turbo 350 or Turbo 400 will have a longer tailshaft than the OE unit, requiring the services of a competent driveshaft shop to shorten (and rebalance) it the appropriate amount (3 inches or less).
Bellhousing Bolt Pattern Identification
2004R
700R4 ('82-92) Transitioned...
700R4 ('82-92)
Transitioned to the 4L60E in '93; 4L60E went into 1-piece bellhousing in '94-97
Turbo 400
Turbo 350
4L60E 2-Piece Bellhousing,...
4L60E 2-Piece Bellhousing, '96-99
4L65E; LS Engine Style (4.8L,...
4L65E; LS Engine Style (4.8L, 5.3L, 5.7L, 6.0L)
Transmission Case Dimensi...
Transmission Case Dimensions
Transmission Fluid Capaci...
Transmission Fluid Capacity
Transmission Identification...
Transmission Identification Guide
Transmission Gear Ratios
Screenshots courtesy of Monster Transmission & Performance.