I learned not to trust mechanics...(questions for timing chain experts)

[amolao]

(1989 S13)
Ok, after a past timing chain install (2 years ago) my chain starting rattling again, I took it upon myself to get it redone by me. Started this past Friday, got all parts,documentation,FSM,etc. Took most of the front components and when I took the timing cover off, I found it to be crack in the lower left corner (see pic) The mechanic that work on the car in the past, crack the cover and put everything back together with LOTS of silicone around that corner. No wonder my car leaked oil in a intermittent way. Now I need a new cover. And the install came to a full stop until next week. Now my two questions:

The 2 oil seals dont look like anything at all like the replacement ones I got from Nissan as shown in this link http://www.autodoctorparts.com/frame...g+Cover+O-Ring

The ones on the car were metal and larger....

The chain guide (NISSAN) replacement is kind of weak and the plastic liner comes off easily, is this the way they are designed??

I need to finish it this week my car goes to the paint shop in 2 weeks....