"Scope and Purpose The purpose of this SAE Recommended Practice is to provide dimensions of clearance envelopes for various types of 6-bolt regular duty and 8-bolt heavy duty truck transmission side-mounted power take-offs. These envelopers are applicable to the clearance required immediately adjacent to the power take-off openings on truck transmissions. Clearance envelopes are provided for the purpose of documenting current practice. It must be recognized that many current designs do not provide these clearances in all orientations and variations. New transmission and power take-off designs should attempt to adhere to these envelopes where practical@ but they should not be constructed to be design restrictive; ultimately@ the actual power take-off clearance must be established for each application. In order to provide realistic envelope sizes@ there are six basic ""types"" of side-mounted P.T.O. All envelopes shown are basic and can be reversed for output to the front or rear of the vehicle. On Types II@ III@ IV and VI@ output shaft locations can additionally be reversed from that shown to the opposite side of the P.T.O. opening centerline. Driveline envelopes@ front or rear@ above or below centerline of openings as required. Must be a cylinder of the minimum diameter shown and fall within the 15-deg maximum half-cone extending vertically up and down and horizontally outward from the driveline cone apex@ for a distance equivalent to that required to bring the P.T.O. driveline beyond points of interference so that auxiliary equipment can be driven. Clearance should be provided on 6-bolt openings on mechanical transmissions for Types I@ II and III with Types I and II being aminimum requirement. Clearance should be provided on automatic transmissions for Types IV and VI depending on 6- or 8-bolt P.T.O openings. Mechanical transmissions with 8-bolt openings should have Type V and VI clearances provided. Direct mount hydraulic pump clearance envelopes are included as an option@ and re commonly used with Types II@ IV and VI P.T.O. envelopes. If pump clearance is restricted it should be evaluated on a specific basis. If specific pump sizes are not available@ direct mount pump clearance envelopes should be used. This SAE Recommended Practice is intended as a guide toward standard practice but may be subject to frequent change to keep pace with experience and technical advance."