Wich type of 5-speed? 76/27 A5 is very rare and if your 350 Sl have one don't swap to 500. If you want you have to reinforce it in several points for the use with 500 M117. In any case the only bold on possibility is using an early 500 engine from a 450 SLC 5.0 because of his old-style endplate (3 speed automatic). if you want to use a norml 500 or 560 engin You have to made a new endplate (if you want there is a boy in Hamburg wich has a CNC programm for it). If you want to use another type of gearbox (tremec or getrag 265) you can do it, making a new endplate an modifing the bellhousing (20 mm to long). In my thread of 108-109 mods you can find some picks of it.
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