(1) The timing cover and timing plates are interchangeable from the 1937 216 to the 1962 235 as well as the 1939 gmc 228 to 1959 fmc 270 and 302. Bottom line... if you have a timing plate from any other 216, 235, 261, 228, 248, pre 1955 270 and 302 gmc motors it will fit on your 58 270 and give you the correct front mount. If you don't have a spare front timing plate, put an add in the parts wanted section. I'm sure one could be had.
(2) The bellhousings will interchange to the motors from 1937 216 to 1960 something 235 and 261 as well as 1939 gmc 228 to 1959 gmc 270 and 302. Bottom line... unbolt the bellhousing that is in your truck now, and bolt it back up to the 58 gmc 270. If the 58 gmc has a 12 volt stomp starter you can use that if your truck is converted to 12 volts. If you want to stay with 6 volts, you need to find a 1954-1955 gmc 6 bolt 6 volt flywheel to use on the 6 bolt 270 crankshaft. There are 12 volt stomp starters available. the 6 and 12 volt starter will bolt up to either bellhousing. It is critical to match the flywheel ring gear to the starter. (168 tooth ring gear = 12 volt flywheel --139 teeth = 6 volt flywheel). A 6 volt starter will work fine on 12 bolts. some people say better. A 12 volt starter will not work on 6 volts.
Last edited by bigbadswingdaddy; 09/27/2012 10:14 PM. Reason: cut off
