Identifying underhood plastics types used on our cars

[4 l-bodies]

Looking to modify a TII black air cleaner box for a larger outlet (mating to a DBB turbo). Trying to identify the type of plastic that was used on these, so I can plastic weld larger outlet on it. Also trying to identify the type of white plastic used on the air cleaner lid and TB bonnet used on the 84-87 T1 cars. This appears to be a different type of plastic. The black plastic on the TII boxes are a slightly greasy plastic and sort of soft. The earlier T1 white plastic is not greasy at all and harder. Didn't have much luck burning them looking for different flame color or odor as noted in FSM. Any plastic experts or gurus out there?
TIA,
Todd

[135sohc]

Polyolefin based.

https://www.polyvance.com/identify.php I use often.

The early T1 air box is probably ABS.

[4 l-bodies]

Polyolefin based.

https://www.polyvance.com/identify.php I use often.

The early T1 air box is probably ABS.

Thanks for the link and your info.