[Rich 5150 69]

Here`s what I`ve found, 1970 cougar tank 21 gallon will fit with trimming of the lower rails approx .75 inches on each side, rear cross member moved back and turned bacwards, shorter that the blazier tank by 4 inches, tank inlet either tru back of bed or under license plate.
1970 cuda tank 19.5 gallon no trimming required, the tank is tappered, 11 inches at the rear end, 6 inches at the rear of the truck, rear inlet same alternative as the couger tank, mopar tanks use a 240 ohmn gauge so either custom gauges or retro fit the stock gauge for 240 ohmn.