This engine is in a 98 model truck so I expected it to have "P" style heads, but upon inspection the engine looks like it has GT heads and not the "P" style. I always look at the angle of the plugs when I can't see any markings. Do these look like GT heads to you here that are much more knowledgeable than me?
https://imageshack.com/a/img923/3781/6UXTJj.jpg
https://imageshack.com/a/img924/6061/DRKMv2.jpg
https://imageshack.com/a/img924/821/q7neVA.jpg
https://imageshack.com/a/img923/3781/6UXTJj.jpg
https://imageshack.com/a/img924/6061/DRKMv2.jpg
https://imageshack.com/a/img924/821/q7neVA.jpg