Between what H-D and custom tanks are available there are a multitude of tanks to chose from but not all fit every model. Early H-D tanks known as FAT-BOB tanks usually fit knuckle, pan and early shovel frames. These tanks had two mounting tabs with holes in the front and a bolt hole in the rear of tank to mount to frame tabs. Softail tanks known as FLAT-SIDE look similar but they have tabs in rear of tanks that bolts go thru to frame. Newer softail tanks are now one piece tanks. The most common things to look for are the size tanks you need and where the petcock is located. Tanks come in 3.5 , 4.2, 5.0, 6.0, and even 7 gallon sizes. The petcock can be either in the middle of left tank, midway between middle and rear and at very rear of tank. You need to know what you are replacing or can fit to your frame before buying a set that isnt described or pictured very accurate. One wise word of caution before spending hard money on that custom paint job, have tanks flushed and pressure tested to ensure they dont leak. Dont want gas spilling out to make that flame job realistic do ya? Hope this helps and keeps you from purchasing the wrong set by mistake. Please take moment to vote either way. thanks. Wheel