Hello
AFIR 574 was used on the head to camhousing in 88 on and from 89on it was used on the case as well. If you check your workshopmanual you will find the new loctite 574 descriped and Porsche recomened to use up all the 573 stock asap. Here in germany 573 is still listet. 573 has a much longer "open time" and will need longer to bond trough. It also doesn´t fill gaps as 574. AFIK the 574 was needed to speed up production process.
For professional use you can get the 57x series in retangular softbagcanisters with 2,5 L contens
574 can be substitutet with 5208
http://www.rolf-richter.de/html/flachendichten.html
http://www.loctite-europe.com/de/loctite_518.htm
http://www.loctite-europe.com/de/loctite_573.htm
http://www.loctite-europe.com/de/loctite_574.htm
http://www.loctite-europe.com/de/PRODUCTS/5208.htm
Grüsse